Spin valve element and thin film magnetic head

ABSTRACT

A spin valve element includes an antiferromagnetic layer, a pinned magnetic layer formed in contact with the antiferromagnetic layer so that the magnetization direction thereof is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer in contact with the pinned magnetic layer, and a free magnetic layer in contact with the nonmagnetic conductive layer. The free magnetic layer includes a nonmagnetic intermediate layer, and first and second free magnetic layers with the nonmagnetic intermediate layer provided therebetween, the second free magnetic layer is formed in contact with the nonmagnetic conductive layer, the first and second free magnetic layers are antiferromagnetically coupled with each other to bring both layers into a ferrimagnetic state, and either of the first and second free magnetic layers comprises a ferromagnetic insulating film. It is thus possible to increase the sensitivity to an external magnetic field, and suppress the occurrence of a shunt loss to increase the rate of change in magnetoresistance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a spin valve element and a thinfilm magnetic head, and particularly to a spin valve element and a thinfilm magnetic head having both high sensitivity to an external magneticfield and a high rate of change in magnetoresistance.

[0003] 2. Description of the Related Art

[0004] Magnetoresistive magnetic heads include a MR (Magnetoresistive)head comprising an element exhibiting a magnetoresistive effect, and aGMR (Giant Magnetoresistive) head comprising an element exhibiting agiant magnetoresistive effect. In the MR head, the element exhibiting amagnetoresistive effect has a single layer structure comprising amagnetic material. On the other hand, in the GMR head, the elementexhibiting a magnetoresistive effect has a multilayer structure in whicha plurality of materials are laminated. Although there are several typesof structures creating the giant magnetoresistive effect, a spin valveelement has a relatively simple structure and exhibits a high rate ofchange in resistance with an external magnetic field.

[0005] Recently, high-density magnetic recording has been increasinglydemanded, and a spin valve element adaptable for higher recordingdensity has increasingly attracted attention.

[0006] A conventional spin valve element is described with reference tothe drawings. FIG. 31 is a schematic sectional view showing aconventional spin valve element 301 as viewed from the magneticrecording medium side.

[0007] Furthermore, shield layers are formed above and below the spinvalve element 301 with gap layers provided therebetween to form areproducing thin film magnetic head comprising the spin valve element301, the gap layers and the shield layers. A recording inductive headmay be laminated on the thin film magnetic head.

[0008] The thin film magnetic head is provided at the trailing side endof a floating slider together with the inductive head to constitute athin film magnetic head which detects a recording magnetic field of amagnetic recording medium such as a hard disk or the like.

[0009] In FIG. 31, the Z direction coincides with the movement directionof the magnetic recording medium, the Y direction coincides with thedirection of a leakage magnetic field from the magnetic recordingmedium, and the X₁ direction coincide with the track width direction ofthe spin valve element 301.

[0010] The spin valve element 301 shown in FIG. 31 is a bottom-typesingle spin valve thin film magnetic element comprising anantiferromagnetic layer 303, a pinned magnetic layer 304, a nonmagneticconductive layer 305, and a free magnetic layer 311, which are laminatedin turn.

[0011] In FIG. 31, reference numeral 300 denotes an insulating layermade of Al₂O₃ or the like, and reference numeral 302 denotes anunderlying layer made of Ta (tantalum) or the like and laminated on theinsulating layer 300. The antiferromagnetic layer 303, the pinnedmagnetic layer 304, the nonmagnetic conductive layer 305 made of Cu orthe like, and the free magnetic layer 311 are laminated on theunderlying layer 302, and a capping layer 320 made of Ta or the like islaminated on the free magnetic layer 311.

[0012] In this way, the layers from the underlying layer 302 to thecapping layer 320 are laminated in turn to constitute a laminate 321having a substantially trapezoidal sectional shape having a widthcorresponding to the track width.

[0013] The pinned magnetic layer 304 is made of, for example, Co, andlaminated in contact with the antiferromagnetic layer 303 so that anexchange coupling magnetic field (exchange anisotropic magnetic field)occurs in the interface between the pinned magnetic layer 304 and theantiferromagnetic layer 303 to pin the magnetization direction of thepinned magnetic layer 304 in the Y direction shown in the drawing.

[0014] The free magnetic layer 311 comprises a nonmagnetic intermediatelayer 309, and first and second free magnetic layers 310 and 308 formedwith the nonmagnetic intermediate layer 309 provided therebetween. Thefirst free magnetic layer 310 is provided on the capping layer 320 sideof the nonmagnetic intermediate layer 309, and the second free magneticlayer 308 is provided on the nonmagnetic conductive layer 305 side ofthe nonmagnetic intermediate layer 309. The thickness of the first freemagnetic layer 310 is slightly larger than the thickness of the secondfree magnetic layer 308. The first and second free magnetic layers 310and 308 are antiferromagnetically coupled with each other so that bothlayers are put into a ferrimagnetic state.

[0015] The first free magnetic layer 310 comprises a ferromagneticconductive film made of a NiFe alloy or the like, and the nonmagneticintermediate layer 309 is made of a nonmagnetic material such as Ru orthe like.

[0016] The second free magnetic layer 308 comprises a anti-diffusionlayer 306 and a ferromagnetic layer 307. Each of the anti-diffusionlayer 306 and the ferromagnetic layer 307 comprises a ferromagneticconductive film, and for example, the anti-diffusion layer 306 is madeof Co, and the ferromagnetic layer 307 is made of a NiFe alloy.

[0017] The anti-diffusion layer 306 is provided for preventing mutualdiffusion between the ferromagnetic layer 307 and the nonmagneticconductive layer 305 to increase the GMR effect (ΔMR) produced in theinterface with the nonmagnetic conductive layer 305.

[0018] Since the first free magnetic layer 310 and the second freemagnetic layer 308 are antiferromagnetically coupled with each other,when the magnetization direction of the first free magnetic layer 310 isoriented in the X₁ direction shown in the drawing by bias layers 332,the magnetization direction of the second free magnetic layer 308 isoriented in the direction opposite to the X₁ direction. At this time,the magnetization of the first free magnetic layer 310 remains to orientthe magnetization direction of the entire free magnetic layer 311 in theX₁ direction shown in the drawing.

[0019] In this way, the first free magnetic layer 310 and the secondfree magnetic layer 308 are antiferromagnetically coupled with eachother so that the magnetization directions are antiparallel to eachother to bring the free magnetic layer 311 into a syntheticferrimagnetic state (synthetic ferrimagnetic free).

[0020] Therefore, the magnetization direction of the free magnetic layer311 crosses the magnetization direction of the pinned magnetic layer304.

[0021] The bias layers 332 are formed on both sides of the laminate 321.The bias layers 332 orient the magnetization direction of the first freemagnetic layer 310 in the X₁ direction to bring the free magnetic layer311 in a single magnetic domain state, suppressing Barkhousen noise ofthe free magnetic layer 311.

[0022] Reference numeral 334 denotes a conductive layer made of Cu orthe like, for applying a sensing current to the laminate 321.

[0023] Furthermore, bias underlying layers 331 made of, for example, Cror the like are provided between the bias layers 332 and the insulatinglayer 300, and between the bias layer 332 and the laminate 321, andintermediate layers 333 made of, for example, Ta or Cr are providedbetween the bias layers 332 and the conductive layers 334.

[0024] In the spin valve thin film magnetic element 301, when themagnetization direction of the free magnetic layer 311, which isoriented in the X₁ direction, is changed by a leakage magnetic fieldfrom the recording medium such as a hard disk or the like, the electricresistance changes with the relation to magnetization of the pinnedmagnetic layer 304 which is pinned in the Y direction, and the leakagemagnetic field from the recording medium is detected by a voltage changebased on the change in the electric resistance.

[0025] The free magnetic layer 311 comprises the first and second freemagnetic layers 310 and 308 antiferromagnetically coupled with eachother, and the magnetization direction of the entire free magnetic layer311 changes with an external magnetic field of small magnitude, therebyincreasing the sensitivity of the spin valve thin film magnetic element301.

[0026] Particularly, the thicknesses of the first and second freemagnetic layers 310 and 308 can be appropriately controlled to decreasethe effective thickness of the free magnetic layer 311 so that themagnetization direction of the free magnetic layer is easily changedwith an external magnetic field of small magnitude to increase thesensitivity of the spin valve element 301.

[0027] The conventional spin valve element 301 comprises the freemagnetic layer 311 having a laminated structure of three layersincluding the first and second free magnetic layers 310 and 308, and thenonmagnetic intermediate layer 309. Therefore, the thickness of thelaminate 321 is increased to cause a shunt of the sensing current. Thiscauses the problem of decreasing conduction electrons flowing throughthe nonmagnetic conductive layer 305 to cause a so-called shunt loss inwhich the rate of change in magnetoresistance of the spin valve element301 is decreased.

[0028] In order to decrease the shunt loss of the spin valve element, itis effective that the free magnetic layer has a single layer structureto decrease the thickness of the laminate. In this case, there is theproblem of slowing down a change in the magnetization direction of thefree magnetic layer in response to an external magnetic field, therebydecreasing the sensitivity to the external magnetic field.

SUMMARY OF THE INVENTION

[0029] The present invention has been achieved in consideration of theabove situation, and an object of the present invention is to provide aspin valve element permitting an increase in the sensitivity to anexternal magnetic field and suppression of a shunt loss to increase therate of change in magnetoresistance. Another object of the presentinvention is to provide a thin film magnetic head comprising the spinvalve element.

[0030] In order to achieve the objects, the present invention has thefollowing construction.

[0031] A spin valve element of the present invention comprises anantiferromagnetic layer, a pinned magnetic layer formed in contact withthe antiferromagnetic layer so that the magnetization direction thereofis pinned by an exchange coupling magnetic field with theantiferromagnetic layer, a nonmagnetic conductive layer in contact withthe pinned magnetic layer, and a free magnetic layer in contact with thenonmagnetic conductive layer, wherein the free magnetic layer comprisesa nonmagnetic intermediate layer, and first and second free magneticlayers with the nonmagnetic intermediate layer provided therebetween,the second free magnetic layer is formed in contact with the nonmagneticconductive layer, the first and second free magnetic layers areantiferromagnetically coupled with each other to bring both layers intoa ferrimagnetic state, and either of the first and second free magneticlayers comprises a ferromagnetic insulating film.

[0032] In the above-described spin valve element, with the first freemagnetic layer comprising the ferromagnetic insulating film, theresistivity of the first free magnetic layer is increased to cause adifficulty in flowing a sensing current in the first free magneticlayer, thereby suppressing a shunt of the sensing current to decrease ashunt loss, and permitting an increase in the rate of change inmagnetoresistance of the spin valve element.

[0033] Since the ferromagnetic insulating film has high resistivity,contact with another layer having low resistivity forms a potentialbarrier in the interface therebetween, and thus up-spin conductionelectrons can be mirror-reflected to extend the mean free path of theup-spin conduction electrons, thereby further increasing the rate ofchange in magnetoresistance of the spin valve element.

[0034] In the spin valve element, with the second free magnetic layercomprising the ferromagnetic insulating film, the up-spin conductionelectrons can be mirror-reflected by the ferromagnetic insulating filmto extend the mean free path of the up-spin conduction electrons, andtrap the up-spin conduction electrons near the nonmagnetic conductivelayer, thereby suppressing a shunt of the sensing current. Therefore,the shunt loss can be decreased to further increase the rate of changein magnetoresistance of the spin valve element.

[0035] In the spin valve element of the present invention, the firstfree magnetic layer may comprises only the ferromagnetic insulating filmor only a first ferromagnetic conductive film.

[0036] Particularly, the first free magnetic layer preferably comprisesa laminate of the ferromagnetic insulating film and the firstferromagnetic conductive film, wherein the first ferromagneticconductive film is formed in contact with the nonmagnetic intermediatelayer, and the ferromagnetic insulating layer and the firstferromagnetic conductive film are ferromagnetically coupled with eachother to cause a ferromagnetic state therebetween. In this case, thethickness s of the first ferromagnetic conductive film is preferably inthe range of 0 nm<s≦3.0 nm.

[0037] In the spin valve element, the ferromagnetic insulating film andthe first ferromagnetic conductive film, which constitute the first freemagnetic layer, are brought into the ferromagnetic state so that themagnetization direction of the whole first free magnetic layer can beoriented in one direction. In addition, the first and second freemagnetic layers are antiferromagnetically coupled with each other toform the ferrimagnetic state, thereby increasing the sensitivity to anexternal magnetic field.

[0038] Furthermore, the first ferromagnetic conductive film is formed incontact with the nonmagnetic intermediate layer, and thus the first andsecond free magnetic layers can be securely antiferromagneticallycoupled with each other to form the ferrimagnetic state, therebyincreasing the sensitivity to an external magnetic field.

[0039] In this case, by setting the thickness s of the firstferromagnetic conductive film in the range of 0 nm<s≦3.0 nm, the firstand second free magnetic layers can be securely antiferromagneticallycoupled with each other.

[0040] In the spin valve element of the present invention, the secondfree magnetic layer may comprise only the ferromagnetic insulating filmor only a second ferromagnetic conductive film.

[0041] Particularly, the second free magnetic layer preferably comprisesa laminate of the ferromagnetic insulating film and the secondferromagnetic conductive film, wherein the second ferromagneticconductive film is formed in contact with the nonmagnetic intermediatelayer, and the ferromagnetic insulating layer and the secondferromagnetic conductive film are ferromagnetically coupled with eachother to cause the ferromagnetic state therebetween.

[0042] In the spin valve element, the ferromagnetic insulating film andthe second ferromagnetic conductive film, which constitute the secondfree magnetic layer, are brought into the ferromagnetic state so thatthe magnetization direction of the whole second free magnetic layer canbe oriented in one direction. In addition, the first and second freemagnetic layers are antiferromagnetically coupled with each other toform the ferrimagnetic state, thereby increasing the sensitivity to anexternal magnetic field.

[0043] Furthermore, the second ferromagnetic conductive film is formedin contact with the nonmagnetic intermediate layer, and thus the firstand second free magnetic layers can be securely antiferromagneticallycoupled with each other to form the ferrimagnetic state, therebyincreasing the sensitivity to an external magnetic field.

[0044] The second free magnetic layer may comprise a laminate of theferromagnetic insulating film and a third ferromagnetic conductive film,wherein the third ferromagnetic conductive film is formed in contactwith the nonmagnetic conductive layer, and the ferromagnetic insulatingfilm and the third ferromagnetic conductive film are ferromagneticallycoupled with each other to form the ferromagnetic state.

[0045] In the spin valve element, the ferromagnetic insulating film andthe third ferromagnetic conductive film, which constitute the secondfree magnetic layer, are brought into the ferromagnetic state so thatthe magnetization direction of the whole second free magnetic layer canbe oriented in one direction. In addition, the first and second freemagnetic layers are antiferromagnetically coupled with each other toform the ferrimagnetic state, thereby increasing the sensitivity to anexternal magnetic field.

[0046] Furthermore, the third ferromagnetic conductive film is formed incontact with the nonmagnetic conductive layer, and thus a greater giantmagnetoresistive effect can be manifested in the interface between thethird ferromagnetic conductive film and the nonmagnetic conductive film,increasing the rate of change in magnetoresistance of the spin valveelement.

[0047] The second free magnetic layer may comprise the ferromagneticinsulating film, and the second and third ferromagnetic conductive filmswith the ferromagnetic insulating film provided therebetween, which areferromagnetically coupled with each other to form the ferromagneticstate.

[0048] In the spin valve element, the ferromagnetic insulating film andthe second and third ferromagnetic conductive films, which constitutethe second free magnetic layer, are brought into the ferromagnetic stateso that the magnetization direction of the whole second free magneticlayer can be oriented in one direction. In addition, the first andsecond free magnetic layers are antiferromagnetically coupled with eachother to form the ferrimagnetic state, thereby increasing thesensitivity to an external magnetic field.

[0049] Also the second ferromagnetic conductive film is formed incontact with the nonmagnetic intermediate layer, and thus the first andsecond free magnetic layers can be securely antiferromagneticallycoupled with each other to form the ferrimagnetic state, therebyincreasing the sensitivity to an external magnetic field.

[0050] Furthermore, the third ferromagnetic conductive film is formed incontact with the nonmagnetic conductive layer, and thus a greater giantmagnetoresistive effect can be manifested in the interface between thethird ferromagnetic conductive film and the nonmagnetic conductive film,increasing the rate of change in magnetoresistance of the spin valveelement.

[0051] In the spin valve element of the present invention, theferromagnetic insulating film is a ferromagnetic insulating oxide filmor ferromagnetic insulating nitride film.

[0052] In the spin valve element of the present invention, theferromagnetic insulating film is a ferromagnetic insulating oxide filmcomprising ferrite composed of Fe—O or M—Fe—O (wherein M is at least oneelement of Mn, Co, Ni, Ba, Sr, Y, Gd, Cu, and Zn).

[0053] As the element M, Mn and Zn, or Ni and Zn are preferablyselected.

[0054] The resistivity of the ferromagnetic insulating film comprisingferrite is preferably 10 μΩ·m (1 Ω·cm) or more.

[0055] Furthermore, the saturation magnetic flux density of theferromagnetic insulating film comprising ferrite is preferably 0.2 T ormore.

[0056] The ferromagnetic insulating film comprising ferrite preferablyhas a composition represented by the following formula:

Fe_(x)M_(y)O_(z)

[0057] wherein M is at least one element of Mn, Co, Ni, Ba, Sr, Y, Gd,Cu, and Zn, and the composition ratios x, y and z by atomic % satisfy20≦x≦40, 10≦y≦20, and 40≦z≦70, respectively.

[0058] In the spin valve element of the present invention, theferromagnetic insulating film is a ferromagnetic insulating oxide filmcomprising a fine crystal phase of bcc structure Fe having an averagecrystal grain diameter of 10 nm or less, and an amorphous phasecontaining large amounts of element T or T′ and O (wherein T representsat least one element of the rare earth elements, and T′ represents atleast one element of Ti, Zr, Hf, V, Nb, Ta, and W), wherein the ratio ofthe fine crystal phase of bcc structure Fe to the entire structure is50% or less.

[0059] The ferromagnetic insulating oxide film is preferably representedby the composition formula below, in which a fine crystal phase of bccstructure Fe having an average crystal grain diameter of 10 nm or lessand an amorphous phase containing large amounts of element T and O aremixed, and the ratio of the fine crystal phase of bcc structure Fe tothe entire structure is 50% or less.

[0060] Namely, the ferromagnetic insulating oxide film is represented bythe composition formula Fe_(a)T_(b)O_(c) wherein T is at least oneelement of the rare earth elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, and Lu), and the composition ratios a, b and c byatomic % satisfy 50≦a≦70, 5≦b≦30, 10≦c≦30, and a+b+c=100.

[0061] The resistivity of the ferromagnetic insulating oxide filmrepresented by the above composition formula is preferably 4 to 10 μΩ·m(400 to 1000 μΩ·cm).

[0062] The ferromagnetic insulating oxide film is preferably representedby the composition formula below, in which a fine crystal phase of bccstructure Fe having an average crystal grain diameter of 10 nm or lessand an amorphous phase containing large amounts of element T and O aremixed, and the ratio of the fine crystal phase of bcc structure Fe tothe entire structure is 50% or less.

[0063] Namely, the ferromagnetic insulating oxide film is represented bythe composition formula Fe_(d)T′_(e)O_(f) wherein T′ is at least oneelement of Ti, Zr, He, V, Nb, Ta, and W, and the composition ratios d, eand f by atomic % satisfy 45≦d≦70, 5≦e≦30, 10≦f≦40, and d+e+f=100.

[0064] The resistivity of the ferromagnetic insulating oxide filmrepresented by the above composition formula is preferably 4 to 2.0×10³μΩ·m (400 to 2.0×10⁵ μΩ·cm).

[0065] In the spin valve element of the present invention, theferromagnetic insulating film is a ferromagnetic insulating nitride filmcomprising a fine crystal phase mainly composed of bcc structure Fehaving an average crystal grain diameter of 10 nm or less, and anamorphous phase mainly composed of a compound of N and at least oneelement D selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, and W,wherein the ratio of the amorphous phase is 50% or more of thestructure.

[0066] The ferromagnetic insulating nitride film is preferablyrepresented by the following composition formula:

Fe_(p)D_(q)N_(r)

[0067] wherein D is at least one element selected from the groupconsisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,Lu, Ti, Zr, Hf, V, Nb, Ta, and W, and the composition ratios p, q and rby atomic % satisfy 60≦d≦80, 10≦q≦15, and 5≦r≦30.

[0068] The resistivity of the ferromagnetic insulating nitride filmrepresented by the above composition formula is preferably 10 μΩ·m ormore.

[0069] In the spin valve element of the present invention, the thicknessu of the ferromagnetic insulating film is preferably in the range of 0.5nm≦u≦10 nm, more preferably in the range of 1.0 nm≦u≦3.0 nm.

[0070] With the second free magnetic layer comprising the ferromagneticinsulating film, the thickness u of the ferromagnetic insulating film isset in the range of 0.5 nm≦u≦10 nm so that the up-spin conductionelectrons moving from the nonmagnetic conductive layer can be mostlymirror-reflected without passing through the ferromagnetic insulatingfilm.

[0071] In another aspect of the present invention, a spin valve elementcomprises an antiferromagnetic layer, a pinned magnetic layer formed incontact with the antiferromagnetic layer so that the magnetizationdirection thereof is pinned by an exchange coupling magnetic field withthe antiferromagnetic layer, a nonmagnetic conductive layer in contactwith the pinned magnetic layer, and a free magnetic layer in contactwith the nonmagnetic conductive layer, wherein the free magnetic layercomprises a nonmagnetic intermediate layer, and first and second freemagnetic layers with the nonmagnetic intermediate layer providedtherebetween, the second free magnetic layer is formed in contact withthe nonmagnetic conductive layer, the first and second free magneticlayers are antiferromagnetically coupled with each other to bring bothlayers into a ferrimagnetic state, and the second free magnetic layercomprises a nonmagnetic intermediate insulating film and a pair offerromagnetic conductive films which are antiferromagnetically coupledwith each other to form a ferrimagnetic state therebetween.

[0072] In the spin valve element, the first and second free magneticlayers are brought into the ferrimagnetic state, and the pair offerromagnetic conductive films which constitute the second free magneticlayers are brought into the ferrimagnetic state with the nonmagneticintermediate insulating film provided therebetween. Therefore, theentire free magnetic layer can be stably brought into the ferrimagneticstate, and the up-spin conduction elections can be mirror-reflected bythe interface between the nonmagnetic intermediate insulating filmhaving high resistivity and one of the ferromagnetic conductive films toextend the mean free path of the up-spin conduction electrons. As aresult, the sensitivity to an external magnetic field can be increased,and the rate of change in magnetoresistance can be increased.

[0073] In a further aspect of the present invention, a spin valveelement comprises an antiferromagnetic layer, a pinned magnetic layerformed in contact with the antiferromagnetic layer so that themagnetization direction thereof is pinned by an exchange couplingmagnetic field with the antiferromagnetic layer, a nonmagneticconductive layer in contact with the pinned magnetic layer, and a freemagnetic layer in contact with the nonmagnetic conductive layer, whereinthe free magnetic layer comprises a nonmagnetic intermediate insulatinglayer, and first and second free magnetic layers with the nonmagneticintermediate insulating layer provided therebetween, the first andsecond free magnetic layers being antiferromagnetically coupled witheach other to form a ferrimagnetic state therebetween.

[0074] In the spin valve element, the first and second free magneticlayers with the nonmagnetic intermediate insulating layer providedtherebetween are brought into the ferrimagnetic state byantiferromagnetic coupling, and the up-spin conduction elections aremirror-reflected by the interface between the nonmagnetic intermediateinsulating film having high resistivity and the second free magneticlayer to extend the mean free path of the up-spin conduction electrons.As a result, the sensitivity to an external magnetic field can beincreased, and the rate of change in magnetoresistance can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0075]FIG. 1 is a schematic sectional view of a spin valve elementaccording to a first embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0076]FIG. 2 is a perspective view of a floating magnetic headcomprising a thin film magnetic head of the present invention;

[0077]FIG. 3 is a schematic sectional view of a principal portion of thefloating magnetic head shown in FIG. 2;

[0078]FIG. 4 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 1;

[0079]FIG. 5 is a schematic drawing illustrating a step of the method ofmanufacturing the spin valve element of the first embodiment of thepresent invention;

[0080]FIG. 6 is a schematic drawing illustrating a step of the method ofmanufacturing the spin valve element of the first embodiment of thepresent invention;

[0081]FIG. 7 is a schematic drawing illustrating a step of the method ofmanufacturing the spin valve element of the first embodiment of thepresent invention;

[0082]FIG. 8 is a schematic drawing illustrating a step of the method ofmanufacturing the spin valve element of the first embodiment of thepresent invention;

[0083]FIG. 9 is a schematic sectional view of a spin valve elementaccording to a second embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0084]FIG. 10 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 9;

[0085]FIG. 11 is a schematic sectional view of a spin valve elementaccording to a third embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0086]FIG. 12 is a schematic sectional view of a spin valve elementaccording to a fourth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0087]FIG. 13 is a schematic sectional view of a spin valve elementaccording to a fifth embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0088]FIG. 14 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 13;

[0089]FIG. 15 is a schematic sectional view of a spin valve elementaccording to a sixth embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0090]FIG. 16 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 15;

[0091]FIG. 17 is a schematic sectional view of a spin valve elementaccording to a seventh embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0092]FIG. 18 is a schematic sectional view of a spin valve elementaccording to an eighth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0093]FIG. 19 is a schematic sectional view of a spin valve elementaccording to a ninth embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0094]FIG. 20 is a schematic sectional view of a spin valve elementaccording to a tenth embodiment of the present invention, as viewed fromthe magnetic recording medium side;

[0095]FIG. 21 is a schematic sectional view of a spin valve elementaccording to an eleventh embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0096]FIG. 22 is a schematic sectional view of a spin valve elementaccording to a twelfth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0097]FIG. 23 is a schematic sectional view of a spin valve elementaccording to a thirteenth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0098]FIG. 24 is a schematic sectional view of a spin valve elementaccording to a fourteenth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0099]FIG. 25 is a schematic sectional view of a spin valve elementaccording to a fifteenth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0100]FIG. 26 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 25;

[0101]FIG. 27 is a schematic sectional view of a spin valve elementaccording to a sixteenth embodiment of the present invention, as viewedfrom the magnetic recording medium side;

[0102]FIG. 28 is a schematic sectional view of a spin valve elementaccording to a seventeenth embodiment of the present invention, asviewed from the magnetic recording medium side;

[0103]FIG. 29 is a schematic drawing illustrating the operation of thespin valve element shown in FIG. 28;

[0104]FIG. 30 is a schematic sectional view of a spin valve elementaccording to an eighteenth embodiment of the present invention, asviewed from the magnetic recording medium side; and

[0105]FIG. 31 is a schematic sectional view of a conventional spin valveelement, as viewed from the magnetic recording medium side.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] Embodiments of the present invention will be described below withreference to FIGS. 1 to 30.

[0107] In FIGS. 1 to 30, the Z direction coincides with the direction ofmovement of a magnetic recording medium, the Y direction coincides withthe direction of a leakage magnetic field from the magnetic recordingmedium, and the X₁ direction coincides with the track width direction ofa spin valve element.

[0108] First Embodiment

[0109]FIG. 1 is a schematic sectional view of a spin valve element 1according to the first embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0110]FIGS. 2 and 3 show a floating magnetic head 150 comprising a thinfilm magnetic head comprising the spin valve element 1.

[0111] The floating magnetic head 150 shown in FIG. 2 mainly comprises aslider 151, a thin film magnetic head h₁ according to the presentinvention and an inductive head h₂, which are provided on the endsurface 151 d of the slider 151. Reference numeral 155 denotes theleading side of the slider 151 on the upstream side in the movementdirection of the magnetic recording medium, and reference numeral 156denotes the trailing side. In the slider 151, rails 151 a and 151 b areformed in the medium-facing surface 152, and air grooves 151 b areformed between the rails.

[0112] As shown in FIGS. 2 and 3, the thin film magnetic head h₁ of thepresent invention comprises an insulating layer 162 formed on the endsurface 151 d of the slider 151, a lower shield layer 163 formed on theinsulating layer 162, a lower gap layer 164 formed on the lower shieldlayer 163, the spin valve element 1 of the present invention, which isformed on the lower gap layer 164 to be exposed from the medium-facingsurface 152, an upper gap layer 166 formed to cover the spin valveelement 1, and an upper shield layer 167 formed to cover the upper gaplayer 166.

[0113] The upper shield layer 167 also serves as a lower core layer ofthe inductive head h₂, which will be described below.

[0114] The inductive head h₂ comprises the lower core layer (uppershield layer) 167, a gap layer 174 laminated on the lower core layer167, a coil 176, an upper insulating layer 177 formed to cover the coil176, and an upper core layer 178 joined to the gap layer 174 and joinedto the lower core layer 167 on the coil 176 side.

[0115] The coil 176 is patterned in a spiral planar shape. The baseportion 178 b of the upper core layer 178 is magnetically connected tothe lower core layer 167 in a substantially central portion of the coil176.

[0116] Furthermore, a core protecting layer 179 made of alumina or thelike is laminated on the upper core layer 178.

[0117] The spin valve element 1 shown in FIG. 1 is a bottom-type singlespin valve thin film magnetic element in which an antiferromagneticlayer 21, a pinned magnetic layer 30, a nonmagnetic conductive layer 29,and a free magnetic layer 50 are laminated in turn.

[0118] In FIG. 1, reference numeral 164 denotes the lower gap layer madeof Al₂O₃ or the like, and reference numeral 23 denotes an underlyinglayer made of Ta (tantalum) or the like and laminated on the lower gaplayer 164. The antiferromagnetic layer 21 is laminated on the underlyinglayer 23, the pinned magnetic layer 30 is laminated on theantiferromagnetic layer 21, and the nonmagnetic conductive layer 29 madeof Cu or the like is laminated on the pinned magnetic layer 30. The freemagnetic layer 50 is laminated on the nonmagnetic conductive layer 29,and a capping layer 24 made of Ta or the like is laminated on the freemagnetic layer 50.

[0119] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 1A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0120] The free magnetic layer 50 comprises a nonmagnetic intermediatelayer 53, and first and second free magnetic layers 51 and 52antiferromagnetically coupled with each other with the nonmagneticintermediate layer 53 provided therebetween to bring both free magneticlayers 51 and 52 into a ferrimagnetic state. The magnetization directionof the entire free magnetic layer 50 is oriented in the X₁ direction.

[0121] The pinned magnetic layer 30 comprises a nonmagnetic layer 33,and first and second pinned magnetic layers 31 and 32antiferromagnetically coupled with each other with the nonmagnetic layer33 provided therebetween to bring both pinned magnetic layers 31 and 32into a ferrimagnetic state. The magnetization direction of the entirepinned magnetic layer 30 is pinned in the Y direction.

[0122] In the spin valve element 1, when the magnetization direction ofthe free magnetic layer 50, which is oriented in the X₁ direction, ischanged by a leakage magnetic field from a recording medium such as ahard disk or the like, the electric resistance changes with the relationto magnetization of the pinned magnetic layer 30, which is pinned in theY direction, i.e., the giant magnetoresistive effect is exhibited, sothat the leakage magnetic field from the recording medium is detected bya voltage change based on the change in the electric resistance.

[0123] A pair of bias layer 332 made of, for example, a Co—Pt(cobalt-platinum) alloy are formed on both sides of the laminate 1A inthe X₁ direction, i.e., in the track width direction. The bias layers332 are formed to extend from the top of the lower gap layer 164 to bothsides 1B of the laminate 1A. The bias layers 332 orient themagnetization direction of the free magnetic layer 50 to decreaseBarkhausen noise of the free magnetic layer 50.

[0124] Reference numeral 334 denotes an electrode layer. The electrodelayers 334 are laminated on the bias layers 332, for applying a sensingcurrent to the laminate 1A.

[0125] Furthermore, bias underlying layers 331 made of, for example, anonmagnetic metal such as Cr are provided between the bias layer 332 andthe lower gap layer 164, and between the bias layers 332 and thelaminate 1A.

[0126] By forming the bias layers 332 on the bias underlying layers 331made of Cr having a body-centered crystal structure (bcc structure), thecoercive force and remanence ratio of the bias layers 332 can beincreased to increase the bias magnetic field necessary for bringing thesecond free magnetic layer 52 into a single domain state.

[0127] Furthermore, intermediate layers 333 made of a nonmagnetic metalsuch as Ta or Cr are provided between the bias layer 332 and theelectrode layers 334.

[0128] In use of Cr for the electrode layers 334, the intermediatelayers 333 made of Ta function as a diffusion barrier to a thermalprocess such as resist curing in a subsequent step, preventingdeterioration in the magnetic properties of the bias layers 332. In useof Ta for the electrode layers 334, the intermediate layers 333 made ofCr has the effect of facilitating the deposition of body-centeredstructure Ta crystal having low resistance on Cr.

[0129] As shown in FIG. 1, the free magnetic layer 50 comprises thenonmagnetic intermediate layer 53, and the first and second freemagnetic layers 51 and 52 with the nonmagnetic intermediate layer 53provided therebetween.

[0130] The first free magnetic layer 51 is provided in contact with thecapping layer 24 on the side of the nonmagnetic intermediate layer 53,which is opposite to the nonmagnetic conductive layer 29 side, and thesecond free magnetic layer 52 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic intermediate layer 53.

[0131] The first free magnetic layer 51 comprises a ferromagneticinsulating film which is ferromagnetic and has high resistivity.Specifically, a ferromagnetic insulating oxide film or a ferromagneticinsulating nitride film can be used.

[0132] The thickness of the first free magnetic layer 51 is preferablyin the range of 1 to 4 nm.

[0133] The nonmagnetic intermediate layer 53 is made of a nonmagneticconductive material such as one of Ru, Rh, Ir, Cr, Re, and Cu, or analloy thereof, more preferably Ru.

[0134] The second free magnetic layer 52 comprises an anti-diffusionfilm 52A and a ferromagnetic film 52B. The anti-diffusion film 52Acomprises a ferromagnetic conductive film of Co or the like, forpreventing mutual diffusion between the ferromagnetic film 52B and thenonmagnetic conductive layer 29.

[0135] Like the anti-diffusion film 52A, the ferromagnetic film 52Bcomprises a ferromagnetic conductive film made of, for example, any oneof Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy,preferably a NiFe alloy.

[0136] The second free magnetic layer 52 may comprise a single layer. Inthis case, the second free magnetic layer 52 is preferably made of anyone of Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0137] The thickness of the second free magnetic layer 52 is preferablyin the range of 2.5 to 4.5 nm, and is more preferably larger than thefirst free magnetic layer 51.

[0138] The first free magnetic layer 51 comprises an insulating filmsuch as a ferromagnetic insulating oxide film or ferromagneticinsulating nitride film, which has a resistivity of about 4 to 2.0×10³μΩ·m, and thus exhibits higher resistivity than the second free magneticlayer comprising ferromagnetic conductive films (the anti-diffusion film52A and the ferromagnetic film 52B) having a resistivity of about 0.3μΩ·m, and the nonmagnetic intermediate layer 53 having a resistivity ofabout 0.1 μΩ·m. Therefore, the sensing current less flows into the firstfree magnetic layer 51.

[0139] Therefore, the sensing current flowing through the laminate 1Amainly flows through the nonmagnetic conductive layer 29, the pinnedmagnetic layer 30 and the second free magnetic layer 52, therebysuppressing a shunt of the sensing current.

[0140] The giant magnetoresistive effect of the spin valve element 1 ismainly manifested in the interfaces between the nonmagnetic conductivelayer 29 and the second free magnetic layer 52 and the pinned magneticlayer 30. Namely, when the magnetization direction of the free magneticlayer 50 is changed by the external magnetic field with the sensingcurrent applied to the laminate 1A, conduction electrons flowing throughthe nonmagnetic conductive layer 29 are scattered at the interfacesbetween the nonmagnetic conductive layer 29 and the free magnetic layer50 and the pinned magnetic layer 30, depending upon the magnetizationdirection of the free magnetic layer 50. This causes a change in themean free path of the conduction electrons, causing a change in the rateof change in magnetoresistance.

[0141] Therefore, the first free magnetic layer 51 comprises aferromagnetic insulating film having high resistivity so as to flow thesensing current in the periphery of the second free magnetic layer 52and the nonmagnetic conductive layer 29, thereby increasing the numberof conduction electrons contributing to the giant magnetoresistiveeffect to increase the rate of change in magnetoresistance.

[0142] In addition, a potential barrier is formed at the interfacebetween the first free magnetic layer 51 comprising a ferromagneticinsulating film and the nonmagnetic intermediate layer 53 comprising anonmagnetic metal or the like due to a great difference in resistivitybetween both layers.

[0143] Of the conduction electrons moving in the nonmagnetic conductivelayer 29 with the sensing current supplied, up-spin conduction electronsare mirror-reflected by the potential barrier while maintaining the spindirection.

[0144] The conduction electrons moving in the nonmagnetic conductivelayer 29 include up-spin conduction electrons and down-spin conductionelectrons which are preset in substantially stochastrically equivalentamounts. The up-spin conduction electrons quite possibly move from thepinned magnetic layer 30 and the nonmagnetic conductive layer 29 to thefree magnetic layer 50 when the magnetization direction of the entirefree magnetic layer 50 becomes parallel to the magnetization directionof the pinned magnetic layer 30.

[0145] The up-spin conduction electrons are reflected at the interfacebetween the first free magnetic layer 51 and the nonmagneticintermediate layer 53 to extend the mean free path, thereby increasingthe difference between the mean free paths of the up-spin conductionelectrons and the down-spin conduction electrons. Therefore, the rate ofchange in magnetoresistance of the spin valve element 1 can beincreased.

[0146] This is described with reference to a schematic drawing of FIG.4.

[0147]FIG. 4 shows a laminate 1G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, the free magnetic layer 50 (the secondfree magnetic layer 52 (the anti-diffusion layer 52A, the ferromagneticlayer 52B), the nonmagnetic intermediate layer 53, the first freemagnetic layer 51) are laminated in turn.

[0148] In FIG. 4, the magnetization direction of the free magnetic layer50 is oriented in the leftward direction in FIG. 4 by the externalmagnetic field, and the magnetization direction of the pinned magneticlayer 30 is pinned in the leftward direction in FIG. 4 by an exchangecoupling magnetic field with the antiferromagnetic layer 21.

[0149] When the sensing current is passed through the laminate 1G shownin FIG. 4, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. The conductionelectrons include the two types of conduction electrons, i.e., theup-spin and down-spin conduction electrons, which are present instochastically substantially equivalent amounts. In FIG. 4, the up-spinconduction electrons are denoted by reference character e₁, and thedown-spin conduction electrons are denoted by reference character e₂.

[0150] The up-spin conduction electrons e₁ quite possibly move from thenonmagnetic conductive layer 29 to the nonmagnetic intermediate layer 53through the second free magnetic layer 52 when the magnetizationdirections of the pinned magnetic layer 30 and the free magnetic layer50 are made parallel to each other by the external magnetic field.

[0151] The up-spin conduction electrons e₁ move to the interface betweenthe nonmagnetic intermediate layer 53 and the first free magnetic layer52, are mirror-reflected by the first free magnetic layer 52 whilemaintaining the spin state, and again move in the nonmagneticintermediate layer 53 and the second free magnetic layer 52.

[0152] In this way, the up-spin conduction electrons e₁ pass through thesecond free magnetic layer 52 and the nonmagnetic intermediate layer 53twice to significantly extend the mean free path to λ⁺.

[0153] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the free magnetic layer 50 (thesecond free magnetic layer 52), and are maintained in the state whereinthe probability of movement to the free magnetic layer 50 remains low,and the mean free path (λ⁻) remains shorter than the mean free path (λ⁺)of the up-spin conduction electrons.

[0154] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 1G.

[0155] Therefore, in the spin valve element 1 of this embodiment, thedifference between the mean free path of the up-spin conductionelectrons e₁ and the mean free path of the down-spin conductionelectrons e₂ can be increased to significantly increase the rate ofchange in magnetoresistance.

[0156] The second free magnetic layer 52 is preferably formed to have athickness slightly larger than the thickness of the first free magneticlayer 51.

[0157] Particularly, assuming that the thicknesses of the first andsecond free magnetic layers 51 and 52 are t₁ and t₂, the saturationmagnetizations of the first and second free magnetic layers 51 and 52are M₁ and M₂, and the magnetic thicknesses of the first and second freemagnetic layers 51 and 52 are M₁·t₁ and M₂·t₂, respectively, themagnetic thicknesses preferably have the relation M₂·t₂>M₁·t₁.

[0158] In this way, where the magnetic thickness of the second freemagnetic layer 52 is larger than the magnetic thickness of the firstfree magnetic layer 51, the magnetization of the second free magneticlayer 52 is left in antiferromagnetic coupling between the first and thesecond free magnetic layers 51 and 52.

[0159] Therefore, as shown in FIG. 1, when the magnetization directionof the second free magnetic layer 52 is oriented in the X₁ direction bythe bias layers 332, the magnetization direction of the first freemagnetic layer 51 is oriented in the direction opposite to the X₁direction to leave the magnetization of the second free magnetic layer52. Therefore, the magnetization direction of the entire free magneticlayer 50 is oriented in the X₁ direction.

[0160] In this way, the first and second free magnetic layers 51 and 52are antiferromagnetically coupled with each other so that themagnetization directions thereof are antiparallel to each other to forma synthetic ferrimagnetic state (synthetic ferrimagnetic free).

[0161] The magnetization direction of the free magnetic layer 50 putinto the ferrimagnetic state can be rotated with a small externalmagnetic field according to the direction of the external magneticfield.

[0162] Since the magnetic thicknesses of the first and second freemagnetic layers 51 and 52 have the relation M₂·t₂>M₁·t₁, the spin flopmagnetic field of the free magnetic layer 50 can be increased so thatthe free magnetic layer 50 can stably maintain the ferrimagnetic state.

[0163] The spin flop magnetic field represents the magnitude of anexternal magnetic field which loses the antiparallel state of themagnetization directions of two magnetic layers when applied to the twomagnetic layers having antiparallel magnetization directions. Therefore,as the spin flop magnetic field of the free magnetic layer 50 increases,the ferrimagnetic state can be more stably maintained even in theexternal magnetic field.

[0164] The first free magnetic layer 51 comprises a ferromagneticinsulating film. Specifically, a ferromagnetic insulating oxide film ora ferromagnetic insulating nitride film can be used.

[0165] An example of the ferromagnetic insulating oxide film whichconstitutes the first free magnetic layer 51 comprises ferrite composedof Fe—O or M—Fe—O (wherein M is at least one element of Mn, Co, Ni, Ba,Sr, Y, Gd, Cu, and Zn). Particularly, Mn and Zn or Ni and Zn arepreferably selected as element M.

[0166] The ferromagnetic insulating oxide film comprising ferrite ispreferably represented by the composition formula Fe_(x)M_(y)O_(z)wherein M is at least one element of Mn, Co, Ni, Ba, Sr, Y, Gd, Cu, andZn, and the composition ratios x, y and z by atomic % satisfy 20≦x≦40,10 ≦y≦20, and 40≦z≦70, respectively.

[0167] The resistivity of the ferromagnetic insulating film comprisingferrite is preferably 10 μΩ·m (1 Ω·cm) or more, and the saturationmagnetic flux density thereof is 0.2 T or more.

[0168] Another example of the ferromagnetic insulating oxide whichconstitutes the first free magnetic layer 51 is a ferromagneticinsulating oxide film in which a fine crystal phase of bcc structure Fehaving an average crystal grain diameter of 10 nm or less and anamorphous phase containing large amounts of element T or T′ and O(wherein T represents at least one element of the rare earth elements,and T′ represents at least one element of Ti, Zr, Hf, V, Nb, Ta, and W)are mixed, and the ratio of the fine crystal phase of bcc structure Feto the entire structure is 50% or less.

[0169] The ferromagnetic insulating oxide film is preferably representedby the composition formula below, in which a fine crystal phase of bccstructure Fe having an average crystal grain diameter of 10 nm or lessand an amorphous phase containing large amounts of element T and O aremixed, and the ratio of the fine crystal phase of bcc structure Fe tothe entire structure is 50% or less.

[0170] Namely, the ferromagnetic insulating oxide film is represented bythe composition formula Fe_(a)T_(b)O_(c) wherein T is at least oneelement of the rare earth elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, and Lu), and the composition ratios a, b and c byatomic % satisfy 50≦a≦70, 5≦b≦30, 10≦c≦30, and a+b+c=100.

[0171] The resistivity of the ferromagnetic insulating oxide filmrepresented by the above composition formula can be set to about 4 to 10μΩ·m (400 to 1000 μΩ·cm).

[0172] Also the ferromagnetic insulating oxide film is preferablyrepresented by the composition formula below, in which a fine crystalphase of bcc structure Fe having an average crystal grain diameter of 10nm or less and an amorphous phase containing large amounts of element Tand O are mixed, and the ratio of the fine crystal phase of bccstructure Fe to the entire structure is 50% or less.

[0173] Namely, the ferromagnetic insulating oxide film is represented bythe composition formula Fe_(d)T′_(e)O_(f) wherein T′ is at least oneelement selected from the group consisting of Ti, Zr, He, V, Nb, Ta, andW, and the composition ratios d, e and f by atomic % satisfy 45≦d≦70,5≦e≦30, 10≦f≦40, and d+e+f=100.

[0174] The resistivity of the ferromagnetic insulating oxide filmrepresented by the above composition formula can be set to 4 to 2.0×10³μΩ·m (400 to 2.0×10⁵ μΩ·cm).

[0175] In the ferromagnetic insulating oxide film, Fe is the maincomponent and carries magnetism. Although the Fe amount is preferably aslarge as possible in order to obtain a high saturation magnetic fluxdensity, the Fe amount of 70 atomic % or more decreases the resistivity.On the other hand, the Fe amount of less than 45 atomic % can increasethe resistivity, but decreases the saturation magnetic flux density.

[0176] The rare earth element T (i.e., at least one of Sc and Y in the3A group in the periodic table, and the lanthanoids such as La, Ce, Pr,Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), or element T′ (atleast one of Ti, Zr, Hf, V, Nb, Ta, and W in the 4A group, 5A group and6A group) is necessary for obtaining soft magnetic properties. Such anelement easily combines with oxygen to form an oxide. The content of theoxide can be controlled to increase the resistivity.

[0177] Also Hf possibly functions to suppress magnetostriction.

[0178] Furthermore, the structure of the ferromagnetic insulating oxidefilm may entirely comprise the amorphous phase, or partly comprise thefine crystal phase of bcc structure Fe. The ferromagnetic insulatingoxide film comprising the fine crystal phase having a large crystalgrain diameter at a high ratio has relatively low resistivity, while theferromagnetic insulating oxide film having a structure mostly comprisingthe amorphous phase containing a large amount of oxygen has highresistivity.

[0179] An example of the ferromagnetic insulating nitride film whichconstitutes the first free magnetic layer 51 is a ferromagneticinsulating nitride film comprising a fine crystal phase mainly composedof bcc structure Fe having an average crystal grain diameter of 10 nm orless, and an amorphous phase mainly composed of a compound of N and atleast one element D selected from the group consisting of La, Ce, Pr,Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta,and W, wherein the ratio of the amorphous phase is at least 50% or moreof the structure.

[0180] The ferromagnetic insulating nitride film is represented by thecomposition formula Fe_(p)D_(q)N_(r) wherein D is at least one elementselected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd,Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, and W, and thecomposition ratios p, q and r by atomic % satisfy 60≦d≦80, 10≦q≦15, and5≦r≦30.

[0181] The resistivity of the ferromagnetic insulating nitride filmrepresented by the above composition formula can be set to about 4 to2.0×10³ μΩ·m.

[0182] In the above composition, the Fe content of 60 atomic % or lessis undesirable because the saturation magnetic flux density issignificantly decreased. The content of element D of 10 atomic % or lessis undesirable because the amorphous phase cannot be obtained, and the N(nitrogen) content of 5 atomic % or less is undesirable because theresistivity and permeability are decreased.

[0183] The ferromagnetic insulating nitride film preferably has astructure in which the ratio of the amorphous phase is 50% or more, andfine crystal grains of body-centered structure Fe having a graindiameter of 10 nm or less and a nitride of element M or Fe areprecipitated in the amorphous phase. The precipitation of Fe finecrystal grains improves the saturation magnetic flux density, and thepresence of a large amount of amorphous phase increases the resistivity.

[0184] The ratio of the Fe fine crystal grains to the structure ispreferably 50% or less. With a crystal grain ratio of over 50%, thepermeability in the high frequency region deteriorates. The crystalgrains precipitated in the structure have a grain diameter of several nmto about 30 nm, and an average grain diameter of 10 nm or less. Byprecipitating such fine crystal grains, the saturation magnetic fluxdensity can be increased. The amorphous phase possibly contributes to anincrease in resistivity, and thus the presence of the amorphous phaseincreases the resistivity.

[0185] The antiferromagnetic layer 21 is preferably made of a PtMnalloy. The PtMn alloy has excellent corrosion resistance, high blockingtemperature, and high exchange coupling magnetic field, as compared witha NiMn alloy and FeMn alloy conventionally used for antiferromagneticlayers.

[0186] The antiferromagnetic layer 21 may be made of an alloyrepresented by X—Mn (wherein X represents one element selected from Pt,Pd, Ru, Ir, Rh, and Os), or X—Pt—Mn (wherein X′ represents ate least oneelement selected from Pd, Cr, Ni, Ru, Ir, Rh, Os, Au, and Ag).

[0187] In the PtMn alloy or the alloy represented by the formula X—Mn,the amount of Pt or X is preferably in the range of 37 to 63 atomic %,more preferably in the range of 44 to 57 atomic %.

[0188] In the alloy represented by the formula X′—Pt—Mn, the amount ofX′ is preferably in the range of 37 to 63 atomic %, more preferably inthe range of 44 to 57 atomic %.

[0189] By heat-treating an alloy having a composition in the aboveappropriate range for the antiferromagnetic layer 21 in a magneticfield, the antiferromagnetic layer 21 producing a high exchange couplingmagnetic field can be obtained. Particularly, by using the PtMn alloy,the excellent antiferromagnetic layer 21 having an exchange couplingmagnetic field of over 6.4×10⁴ A/m, and a high block temperature of 653K(380° C.) at which the exchange coupling magnetic field is lost can beobtained.

[0190] The pinned magnetic layer 30 comprises the nonmagnetic layer 33,and the first and second pinned magnetic layers 31 and 32 with thenonmagnetic layer 33 provided therebetween. The first pinned magneticlayer 31 is provided in contact with the antiferromagnetic layer 21 onthe antiferromagnetic layer 21 side of the nonmagnetic layer 33, and thesecond pinned magnetic layer 32 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic layer 33.

[0191] An exchange coupling magnetic field (exchange anisotropicmagnetic field) occurs in the interface between the first pinnedmagnetic layer 31 and the antiferromagnetic layer 21 to pin themagnetization direction of the first pinned magnetic layer 31 in thedirection opposite to the Y direction.

[0192] The thickness of the first pinned magnetic layer 31 is preferablyslightly different from the thickness of the second pinned magneticlayer 32. In FIG. 2, the thickness of the second pinned magnetic layer32 is larger than that of the first pinned magnetic layer 31.

[0193] The magnetization direction of the first pinned magnetic layer 31is pinned in the direction opposite to the Y direction by the exchangecoupling magnetic field with the antiferromagnetic layer 21, and themagnetization direction of the second pinned magnetic layer 32 is pinnedin the Y direction by antiferromagnetic coupling with the first pinnedmagnetic layer 31.

[0194] Since the magnetization directions of the first and second pinnedmagnetic layers 31 and 32 are antiparallel to each other, the magneticmoments of the first and second pinned magnetic layers 31 and 32 arecanceled by each other. However, the thickness of the second pinnedmagnetic layer 32 is slightly larger, and thus the spontaneousmagnetization of the pinned magnetic layer 30 is slightly left to formthe ferrimagnetic state. The spontaneous magnetization is furtheramplified by the exchange coupling magnetic field with theantiferromagnetic layer 21 to pin the magnetization direction of theentire pinned magnetic layer 30 in the Y direction.

[0195] As a result, the magnetization direction of the free magneticlayer 50 crosses the magnetization direction of the pinned magneticlayer 30.

[0196] Both the first and second pinned magnetic layers 31 and 32 aremade of a ferromagnetic material, for example, such as a NiFe alloy, Co,a CoNiFe alloy, a CoFe alloy, a CoNi alloy, or the like, preferably Co.The first and second pinned magnetic layers 31 and 32 are preferablymade of the same material.

[0197] The nonmagnetic layer 33 is preferably made of a nonmagneticmaterial, for example, one of Ru, Rh, Ir, Cr, Re, and Cu, or an alloythereof, more preferably Ru.

[0198] The nonmagnetic conductive layer 29 is a layer for preventingmagnetic coupling between the pinned magnetic layer 30 and the freemagnetic layer 50, in which the sensing current mainly flows. Thenonmagnetic conductive layer 29 is preferably made of a nonmagneticmaterial having conductivity, for example, Cu, Cr, Au, Ag or the like,more preferably Cu.

[0199] The spin valve element 1 is manufactured, for example, asdescribed below.

[0200] First, as shown in FIG. 5, the underlying layer 23, theantiferromagnetic layer 21, the pinned magnetic layer 30 (the firstpinned magnetic layer 31, the nonmagnetic layer 33, and the secondpinned magnetic layer 32), the nonmagnetic conductive layer 29, the freemagnetic layer 50 (the second free magnetic layer 52, the nonmagneticintermediate layer 53, and the first free magnetic layer 51), and thecapping layer 24 are successively deposited by means of sputtering,vapor deposition, or the like to form a layered film M. Then, a liftoffresist 101 is formed on the layered film M.

[0201] In forming a ferromagnetic insulating oxide film whichconstitutes the first free magnetic layer 51, an oxygen atmosphere ispreferably formed as the deposition atmosphere, while in forming aferromagnetic insulating nitride film, a nitrogen atmosphere ispreferably formed as the deposition atmosphere.

[0202] Next, as shown in FIG. 6, the portions not covered with theliftoff resist 101 are removed by ion milling to form the laminate 1Ahaving an isosceles trapezoidal shape having the inclined side surfaces1B.

[0203] Next, as shown in FIG. 7, the bias underlying layers 331, thebias layers 332, the intermediate layers 333 and the electrode layers334 are successively laminated on the liftoff resist 101 and both sidesof the laminate 1A.

[0204] Finally, as shown in FIG. 8, the liftoff resist 101 is removed toobtain the spin valve element 1.

[0205] In the spin valve element 1, the first free magnetic layer 51comprises the ferromagnetic insulating film, and thus the resistivity ofthe first free magnetic layer 51 is higher than the second free magneticlayer 52 and the nonmagnetic intermediate layer 53, thereby suppressinga shunt of the sensing current. Therefore, the shunt loss can bedecreased to increase the rate of change in magnetoresistance.

[0206] Furthermore, the potential barrier is formed at the interfacebetween the first free magnetic layer 51 comprising the ferromagneticinsulating film, and the nonmagnetic intermediate layer 53 comprising anonmagnetic metal or the like so that the up-spin conduction electronsare mirror-reflected by the potential barrier while maintaining the spindirection. Therefore, the mean free path of the up-spin electrons can beextended to increase the difference between the mean free paths of theup-spin and down-spin conduction electrons, increasing the rate ofchange in magnetoresistance of the spin valve element 1.

[0207] Since the first and second free magnetic layers 51 and 52 whichconstitute the free magnetic layer 50 are brought into the ferrimagneticstate, the magnetization direction of the free magnetic layer 50 can bechanged with a small external magnetic field, thereby increasing thesensitivity of the spin valve element 1 to the external magnetic field.

[0208] Therefore, in the spin valve element 1, the rate of change inmagnetoresistance can be significantly increased due to a reduction inshunt loss and the effect of mirror-reflecting the up-spin conductionelectrons, and the particular effect of increasing the sensitivity tothe external magnetic field by providing the free magnetic layer in theferrimagnetic state can be obtained.

[0209] Second Embodiment

[0210] A second embodiment of the present invention will be describedwith reference to the drawings.

[0211]FIG. 9 is a schematic sectional view of a spin valve element 2according to the second embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0212] Like the spin valve element 1 of the first embodiment, the spinvalve element 2 shown in FIG. 9 is a bottom-type single spin valveelement in which an antiferromagnetic layer 21, a pinned magnetic layer30, a nonmagnetic conductive layer 29, and a free magnetic layer 55 arelaminated in turn.

[0213] In FIG. 9, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer laminated on the lowergap layer 164. The antiferromagnetic layer 21, the pinned magnetic layer30, the nonmagnetic conductive layer 29, the free magnetic layer 55, anda capping layer 24 are laminated in turn on the underlying layer 23.

[0214] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 2A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0215] The spin valve element 2 is different from the spin valve element1 in that the first free magnetic layer 56 comprises a lamination of afirst ferromagnetic insulating film 56A and a first ferromagneticconductive film 56B.

[0216] The antiferromagnetic layer 21, the nonmagnetic conductive layer29, the pinned magnetic layer 30, the bias underlying layers 331, thebias layers 332, the intermediate layers 333, and the electrode layers334 shown in FIG. 9 have the same constructions and are made of the samematerials as the antiferromagnetic layer, the nonmagnetic conductivelayer, the pinned magnetic layer, the bias underlying layers, the biaslayers, the intermediate layers, and the electrode layers of the firstembodiment. Therefore, description of these layers is omitted.

[0217] The free magnetic layer 55 comprises a nonmagnetic intermediatelayer 53, and first and second free magnetic layers 56 and 52antiferromagnetically coupled with each other with the nonmagneticintermediate layer 53 provided therebetween to bring both free magneticlayers 56 and 52 into the ferrimagnetic state.

[0218] Namely, the first free magnetic layer 56 comprises a laminationof the first ferromagnetic insulating film 56A and the firsferromagnetic conductive film 56B, the first ferromagnetic conductivefilm 56B being provided in contact with the nonmagnetic intermediatelayer 53. In addition, the first ferromagnetic insulating film 56A andthe first ferromagnetic conductive film 56B are ferromagneticallycoupled with each other to bring both films in a ferromagnetic state.

[0219] The thickness of the first ferromagnetic insulating film 56A isin the range of 1 nm to 4 nm, and the thickness s of the firstferromagnetic conductive film 56B is in the range of 0 nm<s≦3.0 nm.

[0220] The thickness of the second free magnetic layer 52 is in therange of 2.5 nm to 4.5 nm, and is larger than the first free magneticlayer 56.

[0221] The first ferromagnetic insulating film 56A is equivalent to theferromagnetic insulating film which constitutes the first free magneticlayer of the first embodiment, and comprises an insulating film having aresistivity of about 4 to 2.0×10³ μΩ·m.

[0222] The first ferromagnetic conductive film 56B comprises aferromagnetic film having a resistivity of about 0.3 μΩ·m, and made of,for example, any one of Co, a CoFe alloy, a NiFe alloy, a CoNi alloy,and a CoNiFe alloy.

[0223] The nonmagnetic intermediate layer 53 and the second freemagnetic layer 52 have the same constructions and are made of the samematerials as the nonmagnetic intermediate layer and the second freemagnetic layer of the first embodiment.

[0224] Therefore, the first ferromagnetic insulating film 56A whichconstitutes the first free magnetic layer 56 exhibits higher resistivitythan the second free magnetic layer 52 comprising ferromagneticconductive films (the anti-diffusion film 52A and the ferromagnetic film52B), and the nonmagnetic intermediate film 53, and thus the sensingcurrent less flows in the first free magnetic layer 56.

[0225] Therefore, the sensing current flowing through the laminate 2Amainly flows through the nonmagnetic conductive layer 29, the pinnedmagnetic layer 30 and the second free magnetic layer 52, therebysuppressing a shunt of the sensing current.

[0226] The sensing current is caused to flow through the periphery ofthe second free magnetic layer 52 and the nonmagnetic conductive layer29 to increase the number of conduction electrons contributing to thegiant magnetoresistance, thereby increasing the rate of change inmagnetoresistance.

[0227] Since the first ferromagnetic insulating film 56A and the firstferromagnetic conductive film 56B are ferromagnetically coupled witheach other to bring both films in the ferromagnetic state, themagnetization direction of the entire first free magnetic layer 56 canbe oriented in one direction. Namely, in FIG. 9, when the magnetizationdirection of the second free magnetic layer 52 is oriented in the X₁direction by the bias layers 332, the magnetization direction of theentire first free magnetic layer 56 is oriented in the directionopposite to the X₁ direction. The magnetization of the second freemagnetic layer 52 remains to orient the magnetization direction of theentire free magnetic layer 56 in the X₁ direction.

[0228] Therefore, the first and second free magnetic layers 56 and 52are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0229] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 55 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0230] Furthermore, since the first ferromagnetic conductive film 56B isprovided in contact with the nonmagnetic intermediate layer 53, thefirst and second free magnetic layers 56 and 52 can be securelyantiferromagnetically coupled with each other to increase thesensitivity to the external magnetic field.

[0231] In this case, by setting the thickness s of the firstferromagnetic conductive film 56B in the range of 0 nm<s≦3.0 nm, thefirst and second free magnetic layers 56 and 52 can be securelyantiferromagnetically coupled with each other. With the firstferromagnetic conductive film 56B having a thickness of over 3.0 nm, therate of change in resistance undesirably decreases, while with the firstferromagnetic conductive film 56B having at thickness of 0 nm,antiferromagnetic coupling force between the first and second freemagnetic layer 56 and 52 undesirably weakens.

[0232] In addition, a potential barrier is formed at the interfacebetween the first free ferromagnetic insulating film 56A and the firstferromagnetic conductive film 56B due to a great difference inresistivity between both films. Of the conduction electrons moving inthe nonmagnetic conductive layer 29, up-spin conduction electrons aremirror-reflected by the potential barrier while maintaining the spindirection.

[0233] The up-spin conduction electrons are mirror-reflected at theinterface between the first ferromagnetic insulating film 56A and thefirst ferromagnetic conductive film 56B to extend the mean free path.Like in the first embodiment, therefore, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 2.

[0234] This is described with reference to a schematic drawing of FIG.10.

[0235]FIG. 10 shows a laminate 2G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, the free magnetic layer 55 (the secondfree magnetic layer 52 (the anti-diffusion layer 52A, the ferromagneticlayer 52B), the nonmagnetic intermediate layer 53, the first freemagnetic layer 56 (the first ferromagnetic conductive film 56B and thefirst ferromagnetic insulating film 56A)) are laminated in turn.

[0236] In FIG. 10, the magnetization direction of the free magneticlayer 55 is oriented in the leftward direction in FIG. 10 by theexternal magnetic field, and the magnetization direction of the pinnedmagnetic layer 30 is pinned in the leftward direction in FIG. 10 by anexchange coupling magnetic field with the antiferromagnetic layer 21.

[0237] When the sensing current is passed through the laminate 2G shownin FIG. 10, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. In FIG. 10, theup-spin conduction electrons are denoted by reference character e₁, andthe down-spin conduction electrons are denoted by reference charactere₂.

[0238] The up-spin conduction electrons e₁ quite possibly move from thenonmagnetic conductive layer 29 to the first free magnetic layer 56through the second free magnetic layer 52 and the nonmagneticintermediate layer 53 when the magnetization directions of the pinnedmagnetic layer 30 and the free magnetic layer 55 are made parallel bythe external magnetic field.

[0239] The up-spin conduction electrons e₁ move to the interface betweenthe first ferromagnetic conductive film 56B and the first ferromagneticinsulating film 56A, are mirror-reflected by the first ferromagneticinsulating film 56A which forms the potential barrier while maintainingthe spin state, and again move in the nonmagnetic intermediate layer 53and the second free magnetic layer 52.

[0240] In this way, the up-spin conduction electrons e₁ pass through thesecond free magnetic layer 52, the nonmagnetic intermediate layer 53 andthe first ferromagnetic conductive film 56B twice to significantlyextend the mean free path to λ⁺.

[0241] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the second free magnetic layer52, and are maintained in the state wherein the probability of movementto the free magnetic layer 55 remains low, and the mean free path (λ⁻)remains shorter than the mean free path (λ⁺) of the up-spin conductionelectrons.

[0242] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 2G.

[0243] Therefore, in the spin valve element 2 of this embodiment, thedifference between the mean free path of the up-spin conductionelectrons e₁ and the mean free path of the down-spin conductionelectrons e₂ can be increased to significantly increase the rate ofchange in magnetoresistance of the spin valve element 2.

[0244] The spin valve element 2 is manufactured by substantially thesame method as the spin valve element 1 of the first embodiment exceptthat the first free magnetic layer 56 comprises the first ferromagneticinsulating film 56A and the first ferromagnetic conductive film 56B.

[0245] The spin valve element 2 exhibits not only substantially the sameeffect as the spin valve element 1 of the first embodiment, but also thefollowing effect.

[0246] In the spin valve element 2, the first ferromagnetic conductivefilm 56B is provided between the first ferromagnetic insulating film 56Aand the nonmagnetic intermediate layer 53, and thus the first and secondfree magnetic layers 56 and 52 can be securely antiferromagneticallycoupled with each other to bring both layers into the stableferrimagnetic state, thereby increasing the sensitivity to the externalmagnetic field.

[0247] Third Embodiment

[0248] A third embodiment of the present invention will be describedwith reference to the drawings.

[0249]FIG. 11 is a schematic sectional view of a spin valve element 3according to the third embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0250] Like the spin valve element 1 of the first embodiment, the spinvalve element 3 shown in FIG. 11 is provided on a thin film magnetichead h₁ to constitute a floating magnetic head.

[0251] The spin valve element 3 is a top-type single spin valve elementin which a free magnetic layer 60, a nonmagnetic conductive layer 29, apinned magnetic layer 40, and an antiferromagnetic layer 22 arelaminated in turn.

[0252] In FIG. 11, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 60, the nonmagnetic conductive layer 29, the pinned magnetic layer40, the antiferromagnetic layer 22, and a capping layer 24 are laminatedin turn on the underlying layer 23.

[0253] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 3A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0254] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (a nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 11 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first embodiment. Therefore, description of these layers is omitted.

[0255] As shown in FIG. 11, the free magnetic layer 60 comprises anonmagnetic intermediate layer 63, and first and second free magneticlayers 61 and 62 with the nonmagnetic intermediate layer 63 providedtherebetween.

[0256] The first free magnetic layer 61 is provided in contact with theunderlying layer 23 on the side of the nonmagnetic intermediate layer 63opposite to the nonmagnetic conductive layer side, while the second freemagnetic layer 62 is provided in contact with the nonmagneticintermediate layer 29 on the nonmagnetic conductive layer 29 side of thenonmagnetic intermediate layer 63.

[0257] In FIG. 11, the magnetization direction of the second freemagnetic layer 62 is oriented in the X₁ direction by the bias layers332, and thus the magnetization direction of the first free magneticlayer 61 is oriented in the direction opposite to the X₁ direction. Themagnetization of the second free magnetic layer 62 remains to orient themagnetization direction of the entire free magnetic layer 60 in the X₁direction.

[0258] In this way, the first and second free magnetic layers 61 and 62are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers into the synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0259] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 60 put into theferrimagnetic state can be rotated according to the direction of theexternal magnetic field.

[0260] The first free magnetic layer 61 comprises a ferromagneticinsulating film made of the same material as the first free magneticlayer of the first embodiment, which is ferromagnetic and has highresistivity. The thickness of the first free magnetic layer 61 ispreferably in the range of 1 to 4 nm.

[0261] The nonmagnetic intermediate layer 63 is made of the samematerial as the nonmagnetic intermediate layer of the first embodiment.

[0262] The second free magnetic layer 62 comprises an anti-diffusionfilm 62A and a ferromagnetic film 62B which are made of the samematerials as the anti-diffusion film and the ferromagnetic film of thesecond free magnetic layer of the first embodiment. The second freemagnetic layer 62 may comprise a single layer of a ferromagneticconductive film.

[0263] The first free magnetic layer 61 exhibits higher resistivity thanthe second free magnetic layer 62 comprising ferromagnetic conductivefilms (the anti-diffusion film 62A and the ferromagnetic film 62B), andthe nonmagnetic intermediate film 63, and thus the sensing current lessflows in the first free magnetic layer 61.

[0264] Therefore, the sensing current flowing through the laminate 3Amainly flows through the nonmagnetic conductive layer 29, the pinnedmagnetic layer 40 and the second free magnetic layer 62, therebysuppressing a shunt of the sensing current.

[0265] The sensing current is caused to flow through the periphery ofthe second free magnetic layer 62 and the nonmagnetic conductive layer29 to increase the number of conduction electrons contributing to thegiant magnetoresistance, thereby increasing the rate of change inmagnetoresistance.

[0266] In addition, a potential barrier is formed at the interfacebetween the first free magnetic layer 61 and the nonmagneticintermediate layer 63 due to a great difference in resistivity betweenboth layers. Of the conduction electrons moving in the nonmagneticconductive layer 29, up-spin conduction electrons are mirror-reflectedby the potential barrier while maintaining the spin direction.

[0267] The up-spin conduction electrons are mirror-reflected at theinterface between the first free magnetic layer 61 and the nonmagneticintermediate layer 63 to extend the mean free path. Like in the firstembodiment, therefore, the difference between the mean free paths of theup-spin conduction electrons and the down-spin conduction electrons canbe increased to increase the rate of change in magnetoresistance of thespin valve element 3.

[0268] The antiferromagnetic layer 22 is equivalent to theantiferromagnetic layer of the first embodiment except that thecomposition ratio is slightly different from the first embodiment.

[0269] Namely, the antiferromagnetic layer 22 is made of a PtMn alloy,or an alloy represented by X—Mn (wherein X represents one elementselected from Pt, Pd, Ru, Ir, Rh, and Os), or X—Pt—Mn (wherein X′represents ate least one element selected from Pd, Cr, Ni, Ru, Ir, Rh,Os, Au, and Ag).

[0270] In the PtMn alloy or the alloy represented by the formula X—Mn,the amount of Pt or X is preferably in the range of 37 to 63 atomic %,more preferably in the range of 47 to 57 atomic %. In the alloyrepresented by the formula X′—Pt—Mn, the amount of X′ is preferably inthe range of 37 to 63 atomic %, more preferably in the range of 47 to 57atomic %.

[0271] The spin valve element 3 is manufactured by substantially thesame method as the spin valve element 1 of the first embodiment exceptthat the underlying layer 23, the free magnetic layer 60, thenonmagnetic conductive layer 29, the pinned magnetic layer 40, theantiferromagnetic layer 22, and the capping layer 24 are laminated inturn to form a multilayer film.

[0272] The spin valve element 3 exhibits substantially the same effectas the spin valve element 1 of the first embodiment.

[0273] Fourth Embodiment

[0274] A fourth embodiment of the present invention will be describedwith reference to the drawings.

[0275]FIG. 12 is a schematic sectional view of a spin valve element 4according to the fourth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0276] The spin valve element 4 is a top-type single spin valve elementin which a free magnetic layer 65, a nonmagnetic conductive layer 29, apinned magnetic layer 40, and an antiferromagnetic layer 22 arelaminated in turn.

[0277] In FIG. 11, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 65, the nonmagnetic conductive layer 29, the pinned magnetic layer40, the antiferromagnetic layer 22, and a capping layer 24 are laminatedin turn on the underlying layer 23.

[0278] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 4A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0279] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (a nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 12 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first embodiment. Therefore, description of these layers is omitted.

[0280] The free magnetic layer 65 comprises a nonmagnetic intermediatelayer 63, and first and second free magnetic layers 66 and 62antiferromagnetically coupled with each other with the nonmagneticintermediate layer 63 provided therebetween to bring both layers into aferrimagnetic state.

[0281] The spin valve element 4 is different from the spin valve element3 of the third embodiment in that the first free magnetic layer 66comprises a lamination of a first ferromagnetic insulating film 66A anda first ferromagnetic conductive film 66B.

[0282] The first free magnetic layer 66 comprises a lamination of thefirst ferromagnetic insulating film 66A and the first ferromagneticconductive film 66B, the first ferromagnetic conductive film 66B beingprovided in contact with the nonmagnetic intermediate layer 63. Inaddition, the first ferromagnetic insulating film 66A and the firstferromagnetic conductive film 66B are ferromagnetically coupled witheach other to bring both films in a ferromagnetic state.

[0283] The thickness of the first ferromagnetic insulating film 66A isin the range of 1 nm to 4 nm, and the thickness s of the firstferromagnetic conductive film 66B is in the range of 0 nm<s≦3.0 nm.

[0284] The first ferromagnetic insulating film 66A is equivalent to thefirst ferromagnetic insulating film of the second embodiment, andcomprises an insulating film having a resistivity of about 4 to 2.0×10³μΩ·m.

[0285] The first ferromagnetic conductive film 66B is made of the samematerial as the first ferromagnetic conductive film of the secondembodiment, which is ferromagnetic and has a resistivity of as low asabout 0.3 μΩ·m.

[0286] The nonmagnetic intermediate layer 63 and the second freemagnetic layer 62 have the same constructions and are made of the samematerials as the nonmagnetic intermediate layer and the second freemagnetic layer of the third embodiment.

[0287] The thickness of the second free magnetic layer 62 is in therange of 2.5 nm to 4.5 nm, and is larger than the first free magneticlayer 66.

[0288] Therefore, the first free magnetic layer exhibits higherresistivity than the second free magnetic layer 62 comprisingferromagnetic conductive films (the anti-diffusion film 62A and theferromagnetic film 62B), and the nonmagnetic intermediate film 63, andthus the sensing current less flows in the first free magnetic layer 66.

[0289] Therefore, the sensing current flowing through the laminate 4Amainly flows through the nonmagnetic conductive layer 29, the pinnedmagnetic layer 40 and the second free magnetic layer 62, therebysuppressing a shunt of the sensing current.

[0290] The sensing current is caused to flow through the periphery ofthe second free magnetic layer 62 and the nonmagnetic conductive layer29 to increase the number of conduction electrons contributing to thegiant magnetoresistance, thereby increasing the rate of change inmagnetoresistance.

[0291] Since the first ferromagnetic insulating film 66A and the firstferromagnetic conductive film 66B are ferromagnetically coupled witheach other to bring both films in the ferromagnetic state, themagnetization direction of the entire first free magnetic layer 66 canbe oriented in one direction. Namely, in FIG. 12, when the magnetizationdirection of the second free magnetic layer 62 is oriented in the X₁direction by the bias layers 332, the magnetization direction of theentire first free magnetic layer 66 is oriented in the directionopposite to the X₁ direction. The magnetization of the second freemagnetic layer 62 remains to orient the magnetization direction of theentire free magnetic layer 66 in the X₁ direction to form theferrimagnetic state.

[0292] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 65 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0293] Furthermore, since the first ferromagnetic conductive film 66B isprovided between the first ferromagnetic insulating film 66A and thenonmagnetic intermediate layer 63, the first and second free magneticlayers 66 and 62 can be securely antiferromagnetically coupled with eachother to bring both layers into the ferrimagnetic state, therebyincreasing the sensitivity to the external magnetic field.

[0294] In this case, by setting the thickness s of the firstferromagnetic conductive film 66B in the range of 0 nm<s≦3.0 nm, thefirst and second free magnetic layers 66 and 62 can be securelyantiferromagnetically coupled with each other.

[0295] In addition, a potential barrier is formed at the interfacebetween the first free ferromagnetic insulating film 66A and the firstferromagnetic conductive film 66B due to a great difference inresistivity between both films. Of the conduction electrons moving inthe nonmagnetic conductive layer 29, up-spin conduction electrons aremirror-reflected by the potential barrier while maintaining the spindirection.

[0296] The up-spin conduction electrons are mirror-reflected at theinterface between the first ferromagnetic insulating film 66A and thefirst ferromagnetic conductive film 66B to extend the mean free path.Like in the first embodiment, therefore, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 4.

[0297] The spin valve element 4 is manufactured by substantially thesame method as the spin valve element 2 of the second embodiment exceptthat the underlying layer 23, the free magnetic layer 65, thenonmagnetic conductive layer 29, the pinned magnetic layer 40, theantiferromagnetic layer 22, and the capping layer 24 are laminated inturn to form a multilayer film.

[0298] The spin valve element 4 exhibits substantially the same effectas the spin valve element 2 of the second embodiment.

[0299] Fifth Embodiment

[0300] A fifth embodiment of the present invention will be describedwith reference to the drawings.

[0301]FIG. 13 is a schematic sectional view of a spin valve element 5according to the fifth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0302] The spin valve element 5 shown in FIG. 13 is a bottom-type singlespin valve element in which an antiferromagnetic layer 21, a pinnedmagnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 70 are laminated in turn.

[0303] In FIG. 13, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 70, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0304] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 5A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0305] The antiferromagnetic layer 21, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 13 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first or second embodiment. Therefore, description of these layersis omitted.

[0306] The free magnetic layer 70 comprises a nonmagnetic intermediatelayer 73, and first and second free magnetic layers 71 and 72antiferromagnetically coupled with each other with the nonmagneticintermediate layer 73 provided therebetween to bring both free magneticlayers 71 and 72 into a ferrimagnetic state.

[0307] The first free magnetic layer 71 comprises a ferromagneticconductive film made of, for example, any one of Co, a CoFe alloy, aNiFe alloy, a CoNi alloy, and a CoNiFe alloy, preferably a NiFe alloy.

[0308] The thickness of the first free magnetic layer 71 is preferablyin the range of 0.5 to 4 nm.

[0309] The nonmagnetic intermediate layer 73 is preferably made of anonmagnetic conductive material such as one of Ru, Rh, Ir, Cr, Re, andCu, or an alloy thereof, more preferably Ru.

[0310] The second free magnetic layer 72 comprises a ferromagneticinsulating film which is ferromagnetic and has high resistivity.Examples of such a ferromagnetic insulating film include a ferromagneticinsulating oxide film and a ferromagnetic insulating nitride film. Theferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm is the same as the ferromagnetic insulating oxide film orferromagnetic insulating nitride film which constitutes the first freemagnetic layer of the spin valve element of the first embodiment.

[0311] The thickness of the second free magnetic layer 72 is preferablyin the range of 1.5 nm to 4.5 nm, and is more preferably larger than thefirst free magnetic layer 71.

[0312] The second free magnetic layer 72 is ferromagnetic, and is thusferromagnetically coupled with the first free magnetic layer 71 with thenonmagnetic intermediate layer 73 provided therebetween.

[0313] Therefore, when the magnetization direction of the second freemagnetic layer 72 is oriented in the X₁ direction by the bias layers332, the magnetization direction of the entire first free magnetic layer71 is oriented in the direction opposite to the X₁ direction. Themagnetization of the second free magnetic layer 72 remains to orient themagnetization direction of the entire free magnetic layer 70 in the X₁direction.

[0314] Therefore, the first and second free magnetic layers 71 and 72are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0315] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 70 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0316] In addition, the second free magnetic layer 72 comprises theferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm having a resistivity of 4 to 2.0×10³ μΩ·m, and thus exhibits higherresistivity than the first free magnetic layer 71, the nonmagneticintermediate layer 73 or the nonmagnetic conductive layer 29.Particularly, a potential barrier is formed at the interface between thesecond free magnetic layer 72 and the nonmagnetic conductive layer 29due to a great difference in resistivity between both layers.

[0317] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction, and down-spinconduction electrons are scattered without maintaining the spindirection. The second free magnetic layer 72 comprising theferromagnetic insulating oxide film mirror-reflects only the up-spinconduction electrons.

[0318] The up-spin conduction electrons are mirror-reflected by thesecond free magnetic layer 72 to extend the mean free path. Like in thefirst embodiment, therefore, the difference between the mean free pathsof the up-spin conduction electrons and the down-spin conductionelectrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 5.

[0319] This is described with reference to a schematic drawing of FIG.14.

[0320]FIG. 14 shows a laminate 5G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, and the free magnetic layer 70 (thesecond free magnetic layer 72, the nonmagnetic intermediate layer 73,the first free magnetic layer 71) are laminated in turn.

[0321] In FIG. 14, the magnetization direction of the free magneticlayer 70 is oriented in the leftward direction in FIG. 14 by theexternal magnetic field, and the magnetization direction of the pinnedmagnetic layer 30 is pinned in the leftward direction in FIG. 14 by anexchange coupling magnetic field with the antiferromagnetic layer 21.

[0322] When the sensing current is passed through the laminate 5G shownin FIG. 14, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. In FIG. 14, theup-spin conduction electrons are denoted by reference character e₁, andthe down-spin conduction electrons are denoted by reference charactere₂.

[0323] The up-spin conduction electrons e₁ quite possibly move from thepinned magnetic layer 30 to the second free magnetic layer 72 throughthe nonmagnetic conductive layer 29 when the magnetization directions ofthe pinned magnetic layer 30 and the free magnetic layer 70 are madeparallel by the external magnetic field.

[0324] The up-spin conduction electrons e₁ are mirror-reflected by theinterface between the nonmagnetic conductive layer 29 and the secondfree magnetic layer 72 while maintaining the spin state, and again movein the nonmagnetic conductive layer 29 and the pinned magnetic layer 30.

[0325] In this way, the up-spin conduction electrons e₁ pass through thenonmagnetic conductive layer 29 and the second free magnetic layer 72twice each to significantly extend the mean free path to λ⁺.

[0326] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the second free magnetic layer72, and the mean free path is cut off at the time the down-spinconduction electrons e₂ are scattered by the second free magnetic layer72. Therefore, the mean free path (λ⁻) of the down-spin conductionelectrons e₂ remains shorter than the mean free path (λ⁺) of the up-spinconduction electrons e₁.

[0327] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 5G.

[0328] Therefore, in the spin valve element 5 of this embodiment, thedifference between the mean free path of the up-spin conductionelectrons e₁ and the mean free path of the down-spin conductionelectrons e₂ can be increased to significantly increase the rate ofchange in magnetoresistance of the spin valve element 5.

[0329] The spin valve element 5 is manufactured by substantially thesame method as the spin valve element 1 of the first embodiment exceptthat the second free magnetic layer 72 comprises the ferromagneticinsulating film, and the first free magnetic layer 71 comprises theferromagnetic conductive film.

[0330] In the spin valve element 5, the second free magnetic layer 72comprises the ferromagnetic insulating film, and thus up-spin conductionelectrons can be mirror-reflected by the second free magnetic layer 72to extend the mean free path of the up-spin conduction electrons.Therefore, the difference between the mean free paths of the up-spin anddown-spin conduction electrons can be increased to increase the rate ofchange in magnetoresistance of the spin valve element 5.

[0331] Also, the up-spin conduction electrons are mirror-reflected bythe second free magnetic layer 72 so that the up-spin conductionelectrons 72 can be trapped near the nonmagnetic conductive layer 29.Therefore, a shunt of the sensing current can be suppressed to decreasethe shunt loss, and increase the rate of change in magnetoresistance ofthe spin valve element 5.

[0332] Furthermore, the second free magnetic layer 72 comprises theferromagnetic insulating film and exhibit ferromagnetism, and can thusbe antiferromagnetically coupled with the first free magnetic layer 71to form the ferrimagnetic state. Therefore, the magnetization directionof the free magnetic layer 70 can be changed with a small externalmagnetic field, thereby increasing the sensitivity to the externalmagnetic field.

[0333] Therefore, the spin valve element 5 has the particular effect ofsignificantly increasing the rate of change in magnetoresistance by theeffect of mirror-reflecting up-spin conduction electrons, and increasingthe sensitivity to the external magnetic field by providing the freemagnetic layer in the ferrimagnetic state.

[0334] Sixth Embodiment

[0335] A sixth embodiment of the present invention will be describedwith reference to the drawings.

[0336]FIG. 15 is a schematic sectional view of a spin valve element 6according to the sixth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0337] The spin valve element 6 shown in FIG. 15 is a bottom-type singlespin valve element in which an antiferromagnetic layer 21, a pinnedmagnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 75 are laminated in turn.

[0338] In FIG. 15, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 75, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0339] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 6A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0340] The antiferromagnetic layer 21, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 15 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first or second embodiment. Therefore, description of these layersis omitted.

[0341] The free magnetic layer 75 comprises a nonmagnetic intermediatelayer 73, and first and second free magnetic layers 71 and 76antiferromagnetically coupled with each other with the nonmagneticintermediate layer 73 provided therebetween to bring both free magneticlayers 71 and 76 into a ferrimagnetic state.

[0342] The first free magnetic layer 71 and the nonmagnetic intermediatelayer 73 have the same constructions and are made of the same materialsas the first free magnetic layer and the nonmagnetic intermediate layerof the fifth embodiment.

[0343] The second free magnetic layer 76 comprises a secondferromagnetic insulating film 77 and a third ferromagnetic conductivefilm 78. The second ferromagnetic insulating film 77 is provided incontact with the nonmagnetic intermediate layer 73, and the thirdferromagnetic conductive film 78 is provided in contact with thenonmagnetic conductive layer 29. The second ferromagnetic insulatingfilm 77 and the third ferromagnetic conductive film 78 areferromagnetically coupled with each other to be put into theferromagnetic state.

[0344] The second ferromagnetic insulating film 77 is ferromagnetic andhas high resistivity. Examples of such a ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film, which are the same as the ferromagneticinsulating oxide film or ferromagnetic insulating nitride film whichforms the first free magnetic layer of the spin valve element of thefirst embodiment.

[0345] The third ferromagnetic conductive film 78 is ferromagnetic andhas low resistivity, and is made of, for example, any one of Co, a CoFealloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy, preferably a NiFealloy.

[0346] The thickness of the second ferromagnetic insulating film 77 ispreferably in the range of 0.5 to 10 nm, more preferably in the range of1 to 10 nm. The thickness of the third ferromagnetic conductive film 78is preferably in the range of 1.5 to 4.5 nm.

[0347] The total thickness u of the second free magnetic layer 76 ispreferably in the range of 2.0 to 14.5 nm, more preferably larger thanthe first free magnetic layer 71.

[0348] By setting the thickness u of the second ferromagnetic insulatingfilm 77 in the range of 0.5 nm≦u10≦nm, the up-spin conduction electronsmoving from the nonmagnetic conductive layer 29 can be mostlymirror-reflected without passing through the second ferromagneticinsulating film 77.

[0349] Also, the second ferromagnetic insulating film 77 and the thirdferromagnetic conductive film 78 are ferromagnetically coupled with eachother to be put into the ferromagnetic state so that the magnetizationdirection of the entire second free magnetic layer 76 can be oriented inone direction. Namely, in FIG. 15, when the magnetization direction ofthe second free magnetic layer 76 is oriented in the X₁ direction by thebias layers 332, the magnetization direction of the entire first freemagnetic layer 71 is oriented in the direction opposite to the X₁direction. The magnetization of the second free magnetic layer 76remains to orient the magnetization direction of the entire freemagnetic layer 75 in the X₁ direction.

[0350] Therefore, the first and second free magnetic layers 71 and 76are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in the synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0351] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 75 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0352] In addition, the second ferromagnetic insulating filmconstituting the second free magnetic layer 76 comprises theferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm having a resistivity of 4 to 2.0×10³ μΩ·m, and thus exhibits higherresistivity than the third ferromagnetic conductive film 78. Therefore,a potential barrier is formed at the interface between the secondferromagnetic insulating film 77 and the third ferromagnetic conductivefilm 78.

[0353] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0354] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 77 to extend the mean free path.Like in the first embodiment, therefore, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 6.

[0355] This is described with reference to a schematic drawing of FIG.16.

[0356]FIG. 16 shows a laminate 6G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, the second free magnetic layer 76 (thethird ferromagnetic conductive film 78 and the second ferromagneticinsulating film 77), the nonmagnetic intermediate layer 73, and thefirst free magnetic layer 71 are laminated in turn.

[0357] In FIG. 16, the magnetization direction of the free magneticlayer 75 is oriented in the leftward direction in FIG. 16 by theexternal magnetic field, and the magnetization direction of the pinnedmagnetic layer 30 is pinned in the leftward direction in FIG. 16 by anexchange coupling magnetic field with the antiferromagnetic layer 21.

[0358] When the sensing current is passed through the laminate 6G shownin FIG. 16, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. In FIG. 16, theup-spin conduction electrons are denoted by reference character e₁, andthe down-spin conduction electrons are denoted by reference charactere₂.

[0359] The up-spin conduction electrons e₁ quite possibly move from thepinned magnetic layer 30 to the second ferromagnetic insulating oxidefilm 77 through the nonmagnetic conductive layer 29 when themagnetization directions of the pinned magnetic layer 30 and the freemagnetic layer 75 are made parallel by the external magnetic field.

[0360] The up-spin conduction electrons e₁ are mirror-reflected by theinterface between the second ferromagnetic insulating film 77 and thethird ferromagnetic conductive film 78 while maintaining the spin state,and again move in the third ferromagnetic conductive film 78, thenonmagnetic conductive layer 29 and the pinned magnetic layer 30.

[0361] In this way, the up-spin conduction electrons e₁ pass through thethird ferromagnetic conductive film 78, the nonmagnetic conductive layer29 and the pinned magnetic layer 30 twice each to significantly extendthe mean free path to λ⁺.

[0362] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the second free magnetic layer76, and the mean free path is cut off at the time the down-spinconduction electrons e₂ are scattered by the second free magnetic layer76. Therefore, the mean free path (λ⁻) of the down-spin conductionelectrons e₂ remains shorter than the mean free path (λ⁺) of the up-spinconduction electrons e₁.

[0363] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 6G.

[0364] Therefore, in the spin valve element 6 of this embodiment, thedifference between the mean free path of the up-spin conductionelectrons e₁ and the mean free path of the down-spin conductionelectrons e₂ can be increased to significantly increase the rate ofchange in magnetoresistance of the spin valve element 6.

[0365] Furthermore, since the third ferromagnetic conductive film 78 isprovided in contact with the nonmagnetic conductive layer 29, thegreater giant magnetoresistive effect can be manifested at the interfacebetween the third ferromagnetic conductive film 78 and the nonmagneticconductive layer 29.

[0366] The spin valve element 6 is manufactured by substantially thesame method as the spin valve element 1 of the first embodiment exceptthat the second free magnetic layer 76 comprises the secondferromagnetic insulating film 77 and the third ferromagnetic conductivefilm 78, and the first free magnetic layer 71 comprises theferromagnetic conductive film.

[0367] In the spin valve element 6, the second free magnetic layer 76comprises the second ferromagnetic insulating film 77 and the thirdferromagnetic conductive film 78, and thus up-spin conduction electronscan be mirror-reflected by the second ferromagnetic insulating film 77to extend the mean free path of the up-spin conduction electrons.Therefore, the difference between the mean free paths of the up-spin anddown-spin conduction electrons can be increased to increase the rate ofchange in magnetoresistance of the spin valve element 6.

[0368] Also, the up-spin conduction electrons are mirror-reflected bythe second ferromagnetic insulating film 77 so that the up-spinconduction electrons 72 can be trapped near the nonmagnetic conductivelayer 29. Therefore, a shunt of the sensing current can be suppressed todecrease the shunt loss, and increase the rate of change inmagnetoresistance of the spin valve element 6.

[0369] In addition, since the third ferromagnetic conductive film 78 isprovided in contact with the nonmagnetic conductive layer 29, thegreater giant magnetoresistive effect can be manifested at the interfacebetween the third ferromagnetic conductive film 78 and the nonmagneticconductive layer 29, thereby further increasing the rate of change inmagnetoresistance of the spin valve element 6.

[0370] Furthermore, the second ferromagnetic insulating film 77 and thethird ferromagnetic conductive film 78 are ferromagnetically coupledwith each other to form the ferromagnetic state. Therefore, the secondfree magnetic layer 76 and the first free magnetic layer 71 areantiferromagnetically to bring both layers into the ferrimagnetic state.As a result, the magnetization direction of the free magnetic layer 75can be changed with a small external magnetic field, thereby increasingthe sensitivity of the spin valve element 6 to the external magneticfield.

[0371] Therefore, the spin valve element 6 has the particular effect ofsignificantly increasing the rate of change in magnetoresistance by theeffect of mirror-reflecting up-spin conduction electrons, and increasingthe sensitivity to the external magnetic field by providing the freemagnetic layer in the ferrimagnetic state.

[0372] Seventh Embodiment

[0373] A seventh embodiment of the present invention will be describedwith reference to the drawings.

[0374]FIG. 17 is a schematic sectional view of a spin valve element 7according to the seventh embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0375] The spin valve element 7 shown in FIG. 17 is a bottom-type singlespin valve element in which an antiferromagnetic layer 21, a pinnedmagnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 80 are laminated in turn.

[0376] In FIG. 17, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 80, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0377] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 7A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0378] The free magnetic layer 80 comprises a nonmagnetic intermediatelayer 73, and first and second free magnetic layers 71 and 82antiferromagnetically coupled with each other with the nonmagneticintermediate layer 73 provided therebetween.

[0379] The second free magnetic layer 82 comprises a secondferromagnetic insulating film 77 and a third ferromagnetic conductivefilm 84.

[0380] The antiferromagnetic layer 21, the first free magnetic layer 71,the nonmagnetic intermediate layer 73, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 17 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the first freemagnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first, second, fifth or sixth embodiment. Therefore, description ofthese layers is omitted.

[0381] The spin valve element 7 is different from the spin valve element6 of the sixth embodiment in that the third ferromagnetic conductivefilm 84 which constitutes the second free magnetic layer 82 comprises ananti-diffusion film 84A and a ferromagnetic film 84B.

[0382] Namely, the third ferromagnetic conductive film 84 comprises theanti-diffusion film 84A and the ferromagnetic film 84B which are formedin contact with the nonmagnetic conductive layer 29 and the secondferromagnetic insulating film 77, respectively.

[0383] The anti-diffusion film 84A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 84B and the nonmagnetic conductive layer 29.

[0384] Like the anti-diffusion film 84A, the ferromagnetic film 84Bcomprises a ferromagnetic conductive film, and is made of, for example,any one of Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFealloy, preferably a NiFe alloy.

[0385] The thickness of the anti-diffusion film 84A is preferably in therange of 0.1 to 1.5 nm, and the thickness of the ferromagnetic film 84Bis preferably in the range of 1.4 to 4.5 nm.

[0386] The total thickness of the second free magnetic layer 82 ispreferably in the range of 1.5 to 6.0 nm, and more preferably largerthan the first free magnetic layer 71.

[0387] Also the anti-diffusion film 84A, the ferromagnetic film 84B andthe second ferromagnetic insulating film 77 are ferromagneticallycoupled with each other to be put into the ferromagnetic state so thatthe magnetization direction of the entire second free magnetic layer 82can be oriented in one direction. Namely, in FIG. 17, when themagnetization direction of the second free magnetic layer 82 is orientedin the X₁ direction by the bias layers 332, the magnetization directionof the entire first free magnetic layer 71 is oriented in the directionopposite to the X₁ direction. The magnetization of the second freemagnetic layer 82 remains to orient the magnetization direction of theentire free magnetic layer 80 in the X₁ direction to form theferrimagnetic state.

[0388] The spin valve element 7 is manufactured by substantially thesame method as the spin valve element 6 of the sixth embodiment exceptthat the third ferromagnetic conductive film 84 comprises theanti-diffusion film 84A and the ferromagnetic film 84B.

[0389] The spin valve element 7 exhibits not only the same effect as thespin valve element 6 of the sixth embodiment, but also the followingeffect.

[0390] In the spin valve element 7, the third ferromagnetic conductivefilm 84 comprises the anti-diffusion film 84A and the ferromagnetic film84B to prevent mutual diffusion between the ferromagnetic film 84B andthe nonmagnetic conductive layer 29. Therefore, the greater giantmagnetoresistive effect can be manifested at the interface between thenonmagnetic conductive layer 29 and the anti-diffusion film 84A, therebyincreasing the rate of change in magnetoresistance.

[0391] Eighth Embodiment

[0392] An eighth embodiment of the present invention will be describedwith reference to the drawings.

[0393]FIG. 18 is a schematic sectional view of a spin valve element 8according to the eighth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0394] The spin valve element 8 shown in FIG. 18 is a bottom-type singlespin valve element in which an antiferromagnetic layer 21, a pinnedmagnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 90 are laminated in turn.

[0395] In FIG. 18, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 90, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0396] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 8A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0397] The free magnetic layer 90 comprises a nonmagnetic intermediatelayer 73, and first and second free magnetic layers 71 and 92antiferromagnetically coupled with each other with the nonmagneticintermediate layer 73 provided therebetween.

[0398] The antiferromagnetic layer 21, the first free magnetic layer 71,the nonmagnetic intermediate layer 73, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 18 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the first freemagnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first, second, fifth or sixth embodiment. Therefore, description ofthese layers is omitted.

[0399] The spin valve element 8 is different from the spin valve element6 of the sixth embodiment in that the second free magnetic layer 92comprises two layers including a second ferromagnetic conductive film 93and a second ferromagnetic insulting film 77.

[0400] Namely, the second free magnetic layer 92 comprises the secondferromagnetic conductive film 93 and the second ferromagnetic insulatingfilm 77 which are formed in contact with the nonmagnetic intermediatelayer 73 and the nonmagnetic conductive layer 29, respectively, andwhich are ferromagnetically coupled with each other to form theferromagnetic state.

[0401] The second ferromagnetic insulating film 77 is ferromagnetic andhas high resistivity. Examples of the ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film. The ferromagnetic insulating oxide film orferromagnetic insulating nitride film is the same as the ferromagneticinsulating oxide film or ferromagnetic insulating nitride film whichconstitutes the first free magnetic layer of the spin valve element ofthe first embodiment.

[0402] The second ferromagnetic conductive film 93 is ferromagnetic andhas low resistivity, and is made of, for example, any one of Co, a CoFealloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0403] The thickness of the second ferromagnetic conductive film 93 ispreferably in the range of 1.5 to 4.5 nm, and the thickness u of thesecond ferromagnetic insulating film 77 is preferably in the range of0.5 to 10 nm, and more preferably in the range of 1 to 10 nm.

[0404] The total thickness of the second free magnetic layer 92 ispreferably in the range of 2.0 to 14.5 nm, and more preferably largerthan the first free magnetic layer 71.

[0405] By setting the thickness u of the second ferromagnetic insulatingfilm 77 in the range of 0.5 nm≦u≦10 nm, the up-spin conduction electronsmoving from the nonmagnetic conductive layer 29 can be mostlymirror-reflected by the second ferromagnetic insulating film 77 withoutpassing through the second ferromagnetic insulating film 77.

[0406] Also the second ferromagnetic insulating film 77 and the secondferromagnetic conductive film 93 are ferromagnetically coupled with eachother to be put into the ferromagnetic state so that the magnetizationdirection of the entire second free magnetic layer 92 can be oriented inone direction. Namely, in FIG. 18, when the magnetization direction ofthe second free magnetic layer 92 is oriented in the X₁ direction by thebias layers 332, the magnetization direction of the entire first freemagnetic layer 71 is oriented in the direction opposite to the X₁direction. The magnetization of the second free magnetic layer 92remains to orient the magnetization direction of the entire freemagnetic layer 90 in the X₁ direction.

[0407] Therefore, the first and second free magnetic layers 71 and 92are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0408] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 90 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0409] In addition, the second ferromagnetic insulating film 77comprises the ferromagnetic insulating oxide film or ferromagneticinsulating nitride film having a resistivity of 4 to 2.0×10³ μΩ·m, andthus exhibits higher resistivity than the nonmagnetic conductive layer29 having a resistivity of about 0.3 μΩ·m. Therefore, a potentialbarrier is formed at the interface between the second ferromagneticinsulating film 77 and the nonmagnetic conductive layer 29.

[0410] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0411] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 77 to extend the mean free path.Like in the first embodiment, therefore, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 8.

[0412] The spin valve element 8 is manufactured by substantially thesame method as the spin valve element 6 of the sixth embodiment exceptthat the second free magnetic layer 92 comprises the secondferromagnetic insulating film 77 and the second ferromagnetic conductivefilm 93.

[0413] The spin valve element 8 exhibits not only the same effect as thespin valve element 6 of the sixth embodiment, but also the followingeffect.

[0414] In the spin valve element 8, the second ferromagnetic conductivefilm 93 is formed in contact with the nonmagnetic intermediate layer 73,and thus the first and second free magnetic layers 71 and 92 can besecurely antiferromagnetically coupled with each other to bring bothlayers into the ferrimagnetic state. Therefore, the sensitivity to theexternal magnetic field can be further increased.

[0415] Ninth Embodiment

[0416] A ninth embodiment of the present invention will be describedwith reference to the drawings.

[0417]FIG. 19 is a schematic sectional view of a spin valve element 9according to the ninth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0418] The spin valve element 9 shown in FIG. 19 is a bottom-type singlespin valve element in which an antiferromagnetic layer 21, a pinnedmagnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 100 are laminated in turn.

[0419] In FIG. 19, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 100, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0420] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 9A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0421] The free magnetic layer 100 comprises a nonmagnetic intermediatelayer 73, and first and second free magnetic layers 71 and 102antiferromagnetically coupled with each other with the nonmagneticintermediate layer 73 provided therebetween.

[0422] The antiferromagnetic layer 21, the first free magnetic layer 71,the nonmagnetic intermediate layer 73, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 19 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the first freemagnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first, second, fifth or sixth embodiment. Therefore, description ofthese layers is omitted.

[0423] The spin valve element 9 is different from the spin valve element6 of the sixth embodiment in that the second free magnetic layer 102comprises a second ferromagnetic conductive film 93, a secondferromagnetic insulting film 77, and a third ferromagnetic conductivefilm 84, and in that the third ferromagnetic conductive film 84comprises an anti-diffusion film 84A and a ferromagnetic film 84B.

[0424] Namely, the second free magnetic layer 102 comprises the secondferromagnetic conductive film 93, the second ferromagnetic insulatingfilm 77, and the third ferromagnetic conductive film 84. The second andthird ferromagnetic conductive films 93 and 84 are formed in contactwith the nonmagnetic intermediate layer 73 and the nonmagneticconductive layer 29, respectively. The second ferromagnetic insulatingfilm 77 is held between the second and third ferromagnetic conductivefilms 93 and 84, and the second ferromagnetic insulating film 77 and thesecond and third ferromagnetic conductive films 93 an 84 areferromagnetically coupled with each other to form the ferromagneticstate.

[0425] Like the second ferromagnetic conductive film of the eighthembodiment, the second ferromagnetic conductive film 93 is ferromagneticand has low resistivity, and is made of, for example, any one of Co, aCoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0426] The second ferromagnetic insulating film 77 is ferromagnetic andhas high resistivity. Examples of the ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film. The ferromagnetic insulating oxide film orferromagnetic insulating nitride film is the same as the ferromagneticinsulating oxide film or ferromagnetic insulating nitride film whichconstitutes the first free magnetic layer of the spin valve element ofthe first embodiment.

[0427] Like the third ferromagnetic conductive film of the seventhembodiment, the third ferromagnetic conductive film 84 comprises ananti-diffusion film 84A and a ferromagnetic film 84B, which areferromagnetic and have low resistivity. The anti-diffusion film 84A anda ferromagnetic film 84B are formed in contact with the nonmagneticconductive layer 29 and the second ferromagnetic insulating film 77,respectively, and are ferromagnetically coupled with each other to bringboth films into the ferromagnetic state.

[0428] The anti-diffusion film 84A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 84B and the nonmagnetic conductive layer 29.

[0429] The ferromagnetic film 84B comprises a ferromagnetic conductivefilm made of, for example, any one of Co, a CoFe alloy, a NiFe alloy, aCoNi alloy, and a CoNiFe alloy, preferably a NiFe alloy.

[0430] Like the third ferromagnetic conductive film of the sixthembodiment, the third ferromagnetic conductive film 84 may comprise asingle ferromagnetic conductive film made of any one of Co, a CoFealloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0431] The thickness of the second ferromagnetic conductive film 93 ispreferably in the range of 0.5 to 2.0 nm, and the thickness u of thesecond ferromagnetic insulating film 77 is preferably in the range of0.5 to 10 nm, and more preferably in the range of 1 to 10 nm.

[0432] The thickness of the anti-diffusion film 84A is preferably in therange of 0.1 to 1.5 nm, the thickness of the ferromagnetic film 84B ispreferably in the range of 1.4 to 4.5 nm, and the thickness of the thirdferromagnetic conductive film 84 is preferably in the range of 1.5 to6.0 nm.

[0433] The total thickness of the second free magnetic layer 102 ispreferably in the range of 2.5 to 18.0 nm, and more preferably largerthan the first free magnetic layer 71.

[0434] By setting the thickness u of the second ferromagnetic insulatingfilm 77 in the range of 0.5 nm≦u≦10 nm, the up-spin conduction electronsmoving from the nonmagnetic conductive layer 29 can be mostlymirror-reflected by the second ferromagnetic insulating film 77 withoutpassing through the second ferromagnetic insulating film 77.

[0435] Also the second ferromagnetic insulating film 77 and the secondand third ferromagnetic conductive films 93 and 84 are ferromagneticallycoupled with each other to be put into the ferromagnetic state so thatthe magnetization direction of the entire second free magnetic layer 102can be oriented in one direction. Namely, in FIG. 19, when themagnetization direction of the second free magnetic layer 102 isoriented in the X₁ direction by the bias layers 332, the magnetizationdirection of the first free magnetic layer 71 is oriented in thedirection opposite to the X₁ direction. The magnetization of the secondfree magnetic layer 102 remains to orient the magnetization direction ofthe entire free magnetic layer 100 in the X₁ direction.

[0436] Therefore, the first and second free magnetic layers 71 and 102are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0437] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 100 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0438] In addition, the second ferromagnetic insulating film 77comprises a ferromagnetic insulating oxide film or ferromagneticinsulating nitride film having a resistivity of 4 to 2.0×10³ μΩ·m, andthus exhibits higher resistivity than the third ferromagnetic conductivefilm 84. Therefore, a potential barrier is formed at the interfacebetween the second ferromagnetic insulating film 77 and the thirdnonmagnetic conductive film 84.

[0439] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0440] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 77 to extend the mean free path.Like in the first embodiment, therefore, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 9.

[0441] The spin valve element 9 is manufactured by substantially thesame method as the spin valve element 6 of the sixth embodiment exceptthat the second free magnetic layer 102 comprises the secondferromagnetic insulating film 77 and the second and third ferromagneticconductive films 93 and 84, and that the third ferromagnetic conductivefilm 84 comprises the anti-diffusion film 84A and the ferromagnetic film84B.

[0442] The spin valve element 9 exhibits not only the same effect as thespin valve element 6 of the sixth embodiment, but also the followingeffect.

[0443] In the spin valve element 9, the second ferromagnetic conductivefilm 93 is formed in contact with the nonmagnetic intermediate layer 73,and thus the first and second free magnetic layers 71 and 102 can besecurely antiferromagnetically coupled with each other to bring bothlayers into the ferrimagnetic state. Therefore, the sensitivity to theexternal magnetic field can be further increased.

[0444] Also the third ferromagnetic conductive film 84 is formed incontact with the nonmagnetic conductive layer 29, and thus the greatergiant magnetoresistive effect can be manifested at the interface betweenthe third ferromagnetic conductive film 84 and the nonmagneticconductive layer 29, thereby further increasing the rate of change inmagnetoresistance.

[0445] Furthermore, the third ferromagnetic conductive film 84 comprisesthe anti-diffusion film 84A and the ferromagnetic film 84B to preventmutual diffusion between the ferromagnetic film 84B and the nonmagneticconductive layer 29. Therefore, the greater giant magnetoresistiveeffect can be manifested at the interface between the nonmagneticconductive layer 29 and the anti-diffusion film 84A, thereby increasingthe rate of change in magnetoresistance.

[0446] Tenth Embodiment

[0447] A tenth embodiment of the present invention will be describedwith reference to the drawings.

[0448]FIG. 20 is a schematic sectional view of a spin valve element 10according to the tenth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0449] The spin valve element 10 shown in FIG. 20 is a top-type singlespin valve element in which a free magnetic layer 170, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0450] In FIG. 20, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 170, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0451] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 10A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0452] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (the nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 20 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third or fourth embodiment. Therefore, description of these layersis omitted.

[0453] The free magnetic layer 170 comprises a nonmagnetic intermediatelayer 173, and first and second free magnetic layers 171 and 172antiferromagnetically coupled with each other with the nonmagneticintermediate layer 173 provided therebetween to bring both layers in theferrimagnetic state.

[0454] The first free magnetic layer 171 comprises a ferromagneticconductive film made of, for example, any one of Co, a CoFe alloy, aNiFe alloy, a CoNi alloy, and a CoNiFe alloy, preferably a NiFe alloy.

[0455] The thickness of the first free magnetic layer 171 is preferablyin the range of 0.5 to 3.5 nm.

[0456] The nonmagnetic intermediate layer 173 is preferably made of anonmagnetic conductive material of one of Ru, Rh, Ir, Cr, Re and Cu, oran alloy thereof, more preferably Ru.

[0457] The second free magnetic layer 172 comprises a ferromagneticinsulating film which is ferromagnetic and has high resistivity.Examples of the ferromagnetic insulating film include a ferromagneticinsulating oxide film and a ferromagnetic insulating nitride film. Theferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm is the same as the ferromagnetic insulating oxide film orferromagnetic insulating nitride film which constitutes the first freemagnetic layer of the spin valve element of the first embodiment.

[0458] The thickness of the second free magnetic layer 172 is preferablyin the range of 1.5 to 4.5 nm, and more preferably larger than the firstfree magnetic layer 171.

[0459] The second free magnetic layer 172 is ferromagnetic, and is thusferromagnetically coupled with the first free magnetic layer 171 withthe nonmagnetic intermediate layer 173 provided therebetween.

[0460] Therefore, when the magnetization direction of the second freemagnetic layer 172 is oriented in the X₁ direction by the bias layers332, the magnetization direction of the first free magnetic layer 171 isoriented in the direction opposite to the X₁ direction. Themagnetization of the second free magnetic layer 172 remains to orientthe magnetization direction of the entire free magnetic layer 170 in theX₁ direction.

[0461] Therefore, the first and second free magnetic layers 171 and 172are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0462] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 170 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0463] In addition, the second free magnetic layer 172 comprises aferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm having a resistivity of 4 to 2.0×10³ μΩ·m, and thus exhibits higherresistivity than the first free magnetic layer 171, the nonmagneticintermediate layer 173 or the nonmagnetic conductive layer 29.Therefore, a potential barrier is formed at the interface between thesecond free magnetic layer 172 and the nonmagnetic conductive layer 29due to a large difference in resistivity between the second freemagnetic layer 172 and the nonmagnetic conductive layer 29.

[0464] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction, while thedown-spin conduction electrons are scattered without maintaining thespin direction. Therefore, the second free magnetic layer 172 comprisingthe ferromagnetic insulating oxide film mirror-reflects only the up-spinconduction electrons.

[0465] The up-spin conduction electrons are mirror-reflected by thesecond free magnetic layer 172 to extend the mean free path.

[0466] Namely, the up-spin conduction electrons quite possibly move fromthe pinned magnetic layer 40 to the second free magnetic layer 172through the nonmagnetic conductive layer 29 when the magnetizationdirections of the pinned magnetic layer 40 and the free magnetic layer170 are made parallel by the external magnetic field.

[0467] The up-spin conduction electrons are mirror-reflected at theinterface between the second free magnetic layer 172 and the nonmagneticconductive layer 29 while maintaining the spin state, and again movethrough the nonmagnetic conductive layer 29 and the pinned magneticlayer 40.

[0468] In this way, the up-spin conduction electrons move through thenonmagnetic conductive layer 29 and the pinned magnetic layer 40 twiceeach to significantly extend the mean free path.

[0469] On the other hand, the down-spin conduction electrons have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the second free magnetic layer172, and the mean free path is cut off at the time the down-spinconduction electrons are scattered by the second free magnetic layer172. Therefore, the mean free path of the down-spin conduction electronsremains shorter than the mean free path of the up-spin conductionelectrons.

[0470] In this way, in the spin valve element 10 of this embodiment, thedifference between the mean free paths of the up-spin conductionelectrons and the down-spin conduction electrons is increased by themirror-reflecting effect, thereby significantly improving the rate ofchange in magnetoresistance of the spin valve element 10.

[0471] The spin valve element 10 is manufactured by substantially thesame method as the spin valve element 3 of the third embodiment exceptthat the second free magnetic layer 172 comprises the ferromagneticinsulating film, and the first free magnetic layer 171 comprises theferromagnetic conductive film.

[0472] The spin valve element 9 exhibits substantially the same effectas the spin valve element 5 of the fifth embodiment.

[0473] Eleventh Embodiment

[0474] An eleventh embodiment of the present invention will be describedwith reference to the drawings.

[0475]FIG. 21 is a schematic sectional view of a spin valve element 11according to the eleventh embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0476] The spin valve element 11 shown in FIG. 21 is a top-type singlespin valve element in which a free magnetic layer 175, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0477] In FIG. 20, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 175, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0478] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 11A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0479] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (the nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 20 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third or fourth embodiment. Therefore, description of these layersis omitted.

[0480] The free magnetic layer 175 comprises a nonmagnetic intermediatelayer 173, and first and second free magnetic layers 171 and 176antiferromagnetically coupled with each other with the nonmagneticintermediate layer 173 provided therebetween to bring both layers in theferrimagnetic state.

[0481] The first free magnetic layer 171 and the nonmagneticintermediate layer 173 have the same constructions and are made of thesame materials as the first free magnetic layer and the nonmagneticintermediate layer of the tenth embodiment.

[0482] The second free magnetic layer 176 comprises a lamination of asecond ferromagnetic insulating film 177 and a third ferromagneticconductive film 178. The second ferromagnetic insulating film 177 andthe third ferromagnetic conductive film 178 are formed in contact withthe nonmagnetic intermediate layer 173 and the nonmagnetic conductivelayer 29, respectively. The second ferromagnetic insulating film 177 andthe third ferromagnetic conductive film 178 are ferromagneticallycoupled with each other to bring both films into the ferromagneticstate.

[0483] The second ferromagnetic insulating film 177 is ferromagnetic andhas high resistivity. Examples of the ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film. The ferromagnetic insulating film is the sameas the ferromagnetic insulating oxide film or ferromagnetic insulatingnitride film, which constitutes the first free magnetic layer of thespin valve element of the first embodiment.

[0484] The third ferromagnetic conductive film is ferromagnetic, has lowresistivity, and is made of, for example, any one of Co, a CoFe alloy, aNiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0485] The thickness u of the second ferromagnetic insulating film 177is preferably in the range of 0.5 to 10 nm, more preferably in the rangeof 1 to 10 nm. The thickness of the third ferromagnetic conductive film178 is preferably in the range of 1.5 to 4.5 nm.

[0486] The thickness of the second free magnetic layer 176 is preferablyin the range of 2.0 to 14.5 nm, and more preferably larger than thefirst free magnetic layer 171.

[0487] By setting the thickness u of the second ferromagnetic insulatingfilm 177 in the range of 0.5 nm≦u≦10 nm, the up-spin conductionelectrons moving from the nonmagnetic conductive layer 29 can be mostlymirror-reflected by the second ferromagnetic insulating film 177 withoutpassing through the second ferromagnetic insulating film 177.

[0488] The second ferromagnetic insulating film 177 and the thirdferromagnetic conductive film 178 are ferromagnetically coupled witheach other to bring both films into the ferromagnetic state, and thusthe magnetization direction of the second free magnetic layer 176 can beoriented in one direction. Namely, in FIG. 21, when the magnetizationdirection of the second free magnetic layer 176 is oriented in the X₁direction by the bias layers 332, the magnetization direction of theentire first free magnetic layer 171 is oriented in the directionopposite to the X₁ direction. The magnetization of the second freemagnetic layer 176 remains to orient the magnetization direction of theentire free magnetic layer 175 in the X₁ direction.

[0489] Therefore, the first and second free magnetic layers 171 and 176are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0490] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 175 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0491] In addition, the second ferromagnetic insulating film 177 whichconstitutes the second free magnetic layer 176 comprises a ferromagneticinsulating oxide film or ferromagnetic insulating nitride film having aresistivity of 4 to 2.0×10³ μΩ·m, and thus exhibits higher resistivitythan the third ferromagnetic conductive film 178. Therefore, a potentialbarrier is formed at the interface between the second ferromagneticinsulating film 177 and the third ferromagnetic conductive film 178.

[0492] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0493] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 177 to extend the mean free path.

[0494] Namely, the up-spin conduction electrons quite possibly move fromthe pinned magnetic layer 40 to the second ferromagnetic insulatingoxide film 177 through the nonmagnetic conductive layer 29 when themagnetization directions of the pinned magnetic layer 40 and the freemagnetic layer 175 are made parallel by the external magnetic field.

[0495] The up-spin conduction electrons are mirror-reflected at theinterface between the second ferromagnetic insulating film 177 and thethird ferromagnetic conductive film 178 while maintaining the spinstate, and again move through the third ferromagnetic conductive film178, the nonmagnetic conductive layer 29 and the pinned magnetic layer40.

[0496] In this way, the up-spin conduction electrons move through thenonmagnetic conductive layer 29 and the pinned magnetic layer 40 twiceeach to significantly extend the mean free path.

[0497] In this way, like in the first embodiment, in the spin valveelement 11 of this embodiment, the difference between the mean freepaths of the up-spin conduction electrons and the down-spin conductionelectrons is increased by the mirror-reflecting effect, therebysignificantly improving the rate of change in magnetoresistance of thespin valve element 11.

[0498] Also the third ferromagnetic conductive film 178 is formed incontact with the nonmagnetic conductive layer 29, and thus the greatergiant magnetoresistive effect can be manifested at the interface betweenthe third ferromagnetic conductive film 178 and the nonmagneticconductive layer 29.

[0499] The spin valve element 11 is manufactured by substantially thesame method as the spin valve element 3 of the third embodiment exceptthat the second free magnetic layer 176 comprises the secondferromagnetic insulating film 177 and the second ferromagneticconductive film 178, and the first free magnetic layer 171 comprises theferromagnetic conductive film.

[0500] The spin valve element 11 exhibits substantially the same effectas the spin valve element 6 of the sixth embodiment.

[0501] Twelfth Embodiment

[0502] A twelfth embodiment of the present invention will be describedwith reference to the drawings.

[0503]FIG. 22 is a schematic sectional view of a spin valve element 12according to the twelfth embodiment of the present invention, as viewedfrom the magnetic recording medium side.

[0504] The spin valve element 12 shown in FIG. 22 is a top-type singlespin valve element in which a free magnetic layer 180, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0505] In FIG. 22, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 180, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0506] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 12A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0507] The free magnetic layer 180 comprises a nonmagnetic intermediatelayer 173, and first and second free magnetic layers 171 and 182antiferromagnetically coupled with each other with the nonmagneticintermediate layer 173 provided therebetween.

[0508] The second free magnetic layer 182 comprises a secondferromagnetic insulating film 177 and a third ferromagnetic conductivefilm 184.

[0509] The antiferromagnetic layer 22, the first free magnetic layer171, the nonmagnetic intermediate layer 173, the nonmagnetic conductivelayer 29, the pinned magnetic layer 40 (the nonmagnetic layer 43 andfirst and second pinned magnetic layers 41 and 42), the bias underlyinglayers 331, the bias layers 332, the intermediate layers 333, and theelectrode layers 334 shown in FIG. 22 have the same constructions andare made of the same materials as the antiferromagnetic layer, the firstfree magnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe second or third embodiment. Therefore, description of these layersis omitted.

[0510] The spin valve element 12 is different from the spin valveelement 11 of the eleventh embodiment only in that the thirdferromagnetic conductive film 184 constituting the second free magneticlayer 182 comprises an anti-diffusion film 184A and a ferromagnetic film184B.

[0511] Namely, the third ferromagnetic conductive film 184 comprises theanti-diffusion film 184A and the ferromagnetic film 184B which areformed in contact with the nonmagnetic conductive layer 29 and thesecond ferromagnetic insulating film 177, respectively.

[0512] The anti-diffusion film 184A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 184B and the nonmagnetic conductive layer 29.

[0513] Like the anti-diffusion film 184A, the ferromagnetic film 184Bcomprises a ferromagnetic conductive film made of, for example, any oneof Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy,preferably a NiFe alloy.

[0514] The thickness of the anti-diffusion film 184A is preferably inthe range of 0.1 to 1.5 nm, and the thickness of the ferromagnetic film184B is preferably in the range of 1.4 to 4.5 nm.

[0515] The thickness of the entire second free magnetic layer 182 ispreferably in the range of 1.5 to 6.0 nm, and more preferably largerthan the first free magnetic layer 171.

[0516] The anti-diffusion film 184A, the ferromagnetic film 184B and thesecond ferromagnetic insulating film 177 are ferromagnetically coupledwith each other to bring the films into the ferromagnetic state, andthus the magnetization direction of the second free magnetic layer 182can be oriented in one direction. Namely, in FIG. 22, when themagnetization direction of the second free magnetic layer 182 isoriented in the X₁ direction by the bias layers 332, the magnetizationdirection of the entire first free magnetic layer 171 is oriented in thedirection opposite to the X₁ direction. The magnetization of the secondfree magnetic layer 182 remains to orient the magnetization direction ofthe entire free magnetic layer 180 in the X₁ direction to form theferrimagnetic state.

[0517] The spin valve element 12 is manufactured by substantially thesame method as the spin valve element 11 of the eleventh embodimentexcept that the third ferromagnetic conductive film 184 comprises theanti-diffusion film 184A and the ferromagnetic film 184B.

[0518] The spin valve element 12 exhibits substantially the same effectas the spin valve element 7 of the seventh embodiment.

[0519] Thirteenth Embodiment

[0520] A thirteenth embodiment of the present invention will bedescribed with reference to the drawings.

[0521]FIG. 23 is a schematic sectional view of a spin valve element 13according to the thirteenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0522] The spin valve element 13 shown in FIG. 23 is a top-type singlespin valve element in which a free magnetic layer 190, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0523] In FIG. 23, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 190, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0524] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 13A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0525] The free magnetic layer 190 comprises a nonmagnetic intermediatelayer 173, and first and second free magnetic layers 171 and 192 withthe nonmagnetic intermediate layer 173 provided therebetween.

[0526] The antiferromagnetic layer 22, the first free magnetic layer171, the nonmagnetic intermediate layer 173, the nonmagnetic conductivelayer 29, the pinned magnetic layer 40 (the nonmagnetic layer 43 andfirst and second pinned magnetic layers 41 and 42), the bias underlyinglayers 331, the bias layers 332, the intermediate layers 333, and theelectrode layers 334 shown in FIG. 23 have the same constructions andare made of the same materials as the antiferromagnetic layer, the firstfree magnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third or fourth embodiment. Therefore, description of these layersis omitted.

[0527] The spin valve element 13 is different from the spin valveelement 11 of the eleventh embodiment only in that the second freemagnetic layer 192 comprises three layers of a second ferromagneticconductive film 193, a second ferromagnetic insulating film 177 and athird ferromagnetic conductive film 178.

[0528] The second free magnetic layer 192 comprises the secondferromagnetic conductive film 193 and the second ferromagneticinsulating film 177 which are formed in contact with the nonmagneticintermediate layer 173 and the nonmagnetic conductive layer 29,respectively, and which are brought into the ferromagnetic state byferromagnetic coupling.

[0529] The second ferromagnetic insulating film 177 is ferromagnetic andhas high resistivity. Examples of such a ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film, which are the same as the ferromagneticinsulating oxide film or ferromagnetic insulating nitride film whichforms the first free magnetic layer of the spin valve element of thefirst embodiment.

[0530] The second ferromagnetic conductive film 193 is ferromagnetic andhas low resistivity, and is made of, for example, any one of Co, a CoFealloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0531] The thickness of the second ferromagnetic conductive film 193 ispreferably in the range of 1.5 to 4.5 nm, and the thickness u of thesecond ferromagnetic insulating film 177 is preferably in the range of0.5 to 10 nm, more preferably in the range of 1 to 10 nm.

[0532] The thickness of the entire second free magnetic layer 192 ispreferably in the range of 1.5 to 4.5 nm, and more preferably largerthan the first free magnetic layer 171.

[0533] By setting the thickness u of the second ferromagnetic insulatingfilm 177 in the range of 0.5 nm≦u≦10 nm, the up-spin conductionelectrons moving from the nonmagnetic conductive layer 29 is mostlymirror-reflected by the second ferromagnetic insulating film 177 withoutpassing through the second ferromagnetic insulating film 177.

[0534] The second ferromagnetic insulating film 177 and the secondferromagnetic conductive film 193 are brought into the ferromagneticstate by ferromagnetic coupling, and thus the magnetization direction ofthe second free magnetic layer 192 can be oriented in one direction.Namely, in FIG. 23, when the magnetization direction of the second freemagnetic layer 192 is oriented in the X₁ direction by the bias layers332, the magnetization direction of the entire first free magnetic layer171 is oriented in the direction opposite to the X₁ direction. Themagnetization of the second free magnetic layer 192 remains to orientthe magnetization direction of the entire free magnetic layer 190 in theX₁ direction.

[0535] Therefore, the first and second free magnetic layers 171 and 192are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0536] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 190 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0537] In addition, the second ferromagnetic insulating film 177comprises the ferromagnetic insulating oxide film or ferromagneticinsulating nitride film having a resistivity of 4 to 2.0×10³ μΩ·m, andthus exhibits higher resistivity than the nonmagnetic conductive layer29. Therefore, a potential barrier is formed at the interface betweenthe second ferromagnetic insulating film 177 and the nonmagneticconductive layer 29.

[0538] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0539] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 177 to extend the mean free path.

[0540] The up-spin conduction electrons quite possibly move from thepinned magnetic layer 40 to the second ferromagnetic insulating oxidefilm 177 through the nonmagnetic conductive layer 29 when themagnetization directions of the pinned magnetic layer 40 and the freemagnetic layer 190 are made parallel by the external magnetic field.

[0541] The up-spin conduction electrons are mirror-reflected at theinterface between the second ferromagnetic insulating film 177 and thenonmagnetic conductive film 29 while maintaining the spin state, andagain move in the nonmagnetic conductive layer 29 and the pinnedmagnetic layer 40.

[0542] In this way, the up-spin conduction electrons pass through thenonmagnetic conductive layer 29 and the pinned magnetic layer 40 twiceeach to significantly extend the mean free path.

[0543] Therefore, like in the first embodiment, in the spin valveelement 13 of this embodiment, the difference between the mean freepaths of the up-spin conduction electrons and down-spin conductionelectrons is increased by the mirror reflecting effect, therebysignificantly increasing the rate of change in magnetoresistance of thespin valve element 13.

[0544] The spin valve element 13 is manufactured by substantially thesame method as the spin valve element 10 of the tenth embodiment exceptthat the second free magnetic layer 192 comprises the secondferromagnetic insulating film 177 and the second ferromagneticconductive film 193.

[0545] The spin valve element 13 exhibits substantially the same effectas the spin valve element 8 of the eighth embodiment.

[0546] Fourteenth Embodiment

[0547] A fourteenth embodiment of the present invention will bedescribed with reference to the drawings.

[0548]FIG. 24 is a schematic sectional view of a spin valve element 14according to the fourteenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0549] The spin valve element 14 shown in FIG. 24 is a top-type singlespin valve element in which a free magnetic layer 200, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0550] In FIG. 24, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 200, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0551] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 14A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0552] The free magnetic layer 200 comprises a nonmagnetic intermediatelayer 173, and first and second free magnetic layers 171 and 202 withthe nonmagnetic intermediate layer 173 provided therebetween.

[0553] The antiferromagnetic layer 22, the first free magnetic layer171, the nonmagnetic intermediate layer 173, the nonmagnetic conductivelayer 29, the pinned magnetic layer 40 (the nonmagnetic layer 43 andfirst and second pinned magnetic layers 41 and 42), the bias underlyinglayers 331, the bias layers 332, the intermediate layers 333, and theelectrode layers 334 shown in FIG. 24 have the same constructions andare made of the same materials as the antiferromagnetic layer, the firstfree magnetic layer, the nonmagnetic intermediate layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third or fourth embodiment. Therefore, description of these layersis omitted.

[0554] The spin valve element 14 is different from the spin valveelement 13 of the thirteenth embodiment only in that the second freemagnetic layer 202 comprises a second ferromagnetic conductive film 193,a second ferromagnetic insulating film 177 and a third ferromagneticconductive film 184, and the third ferromagnetic conductive film 184comprises an anti-diffusion film 184A and a ferromagnetic film 184B.

[0555] The second free magnetic layer 202 comprises the secondferromagnetic conductive film 193, the second ferromagnetic insulatingfilm 177 and the third ferromagnetic conductive film 184. The secondferromagnetic conductive film 193 and the third ferromagnetic conductivefilm 184 are formed in contact with the nonmagnetic intermediate layer173 and the nonmagnetic conductive layer 29, respectively, the secondferromagnetic insulating film 177 being held between the second andthird ferromagnetic conductive films 193 and 184. The secondferromagnetic insulating film 177 and the second and third ferromagneticconductive films 193 and 184 are brought into the ferromagnetic state byferromagnetic coupling.

[0556] The second ferromagnetic conductive film 193 comprises the samesecond ferromagnetic conductive film of the thirteenth embodiment, whichis ferromagnetic, has low resistivity, and is made of, for example, anyone of Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0557] The second ferromagnetic insulating film 177 is ferromagnetic andhas high resistivity. Examples of such a ferromagnetic insulating filminclude a ferromagnetic insulating oxide film and a ferromagneticinsulating nitride film, which are the same as the ferromagneticinsulating oxide film or ferromagnetic insulating nitride film whichforms the first free magnetic layer of the spin valve element of thefirst embodiment.

[0558] Like the third ferromagnetic conductive film of the twelfthembodiment, the third ferromagnetic conductive film 184 comprises theanti-diffusion film 184A and the ferromagnetic film 184B, both of whichare ferromagnetic and have low resistivity. The anti-diffusion film 184Aand the ferromagnetic film 184B are formed in contact with thenonmagnetic conductive layer 29 and the second ferromagnetic insulatingfilm 177, respectively, and are brought into the ferromagnetic state byferromagnetic coupling.

[0559] The anti-diffusion film 184A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 184B and the nonmagnetic conductive layer 29.

[0560] The ferromagnetic film 184B comprises a ferromagnetic conductivefilm made of, for example, any one of Co, a CoFe alloy, a NiFe alloy, aCoNi alloy, and a CoNiFe alloy, preferably a NiFe alloy.

[0561] Like the third ferromagnetic conductive film of the eleventhembodiment, the third ferromagnetic conductive film 184 may comprise asingle layer of a ferromagnetic conductive film made of any one of Co, aCoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy.

[0562] The thickness of the second ferromagnetic conductive film 193 ispreferably in the range of 0.5 to 2.5 nm, and the thickness of thesecond ferromagnetic insulating film 177 is preferably in the range of0.5 to 10 nm, more preferably in the range of 1 to 10 nm.

[0563] The thickness of the anti-diffusion film 184A is preferably inthe range of 0.1 to 1.5 nm, the thickness of the ferromagnetic film 184Bis preferably in the range of 1.4 to 4.5 nm, and the thickness of thethird ferromagnetic conductive film 184B is preferably in the range of1.5 to 6.0 nm.

[0564] The thickness of the entire second free magnetic layer 202 ispreferably in the range of 2.5 to 18.5 nm, and more preferably largerthan the first free magnetic layer 171.

[0565] By setting the thickness u of the second ferromagnetic insulatingfilm 177 in the range of 0.5 nm≦u≦10 nm, the up-spin conductionelectrons moving from the nonmagnetic conductive layer 29 is mostlymirror-reflected by the second ferromagnetic insulating film 177 withoutpassing through the second ferromagnetic insulating film 177.

[0566] The second ferromagnetic insulating film 177 and the second andthird ferromagnetic conductive films 193 and 184 are ferromagneticallycoupled with each other to bring the films into the ferromagnetic state,and thus the magnetization direction of the second free magnetic layer202 can be oriented in one direction. Namely, in FIG. 24, when themagnetization direction of the second free magnetic layer 202 isoriented in the X₁ direction by the bias layers 332, the magnetizationdirection of the entire first free magnetic layer 171 is oriented in thedirection opposite to the X₁ direction. The magnetization of the secondfree magnetic layer 202 remains to orient the magnetization direction ofthe entire free magnetic layer 200 in the X₁ direction to form theferrimagnetic state.

[0567] Therefore, the first and second free magnetic layers 171 and 202are antiferromagnetically coupled with each other so that themagnetization directions are antiparallel to each other to bring bothlayers in a synthetic ferrimagnetic state (synthetic ferrimagneticfree).

[0568] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 200 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0569] In addition, the second ferromagnetic insulating film 177comprises the ferromagnetic insulating oxide film or ferromagneticinsulating nitride film having a resistivity of 4 to 2.0×10³ μΩ·m, andthus exhibits higher resistivity than the third ferromagnetic conductivefilm 184. Therefore, a potential barrier is formed at the interfacebetween the second ferromagnetic insulating film 177 and the thirdferromagnetic conductive film 184.

[0570] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, up-spin conduction electrons are mirror-reflected by thepotential barrier while maintaining the spin direction.

[0571] The up-spin conduction electrons are mirror-reflected by thesecond ferromagnetic insulating film 177 to extend the mean free path.As a result, like in the first embodiment, the difference between themean free paths of the up-spin conduction electrons and down-spinconduction electrons can-be increased to significantly increase the rateof change in magnetoresistance of the spin valve element 14.

[0572] The spin valve element 14 is manufactured by substantially thesame method as the spin valve element 10 of the tenth embodiment exceptthat the second free magnetic layer 202 comprises the secondferromagnetic insulating film 177 and the second and third ferromagneticconductive films 193 and 184, and the third ferromagnetic conductivefilm 184 comprises the anti-diffusion film 184A and the ferromagneticfilm 184B.

[0573] The spin valve element 14 exhibits substantially the same effectas the spin valve element 9 of the ninth embodiment.

[0574] Fifteenth Embodiment

[0575] A fifteenth embodiment of the present invention will be describedwith reference to the drawings.

[0576]FIG. 25 is a schematic sectional view of a spin valve element 15according to the fifteenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0577] The spin valve element 15 shown in FIG. 25 is a bottom-typesingle spin valve element in which an antiferromagnetic layer 21, apinned magnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 210 are laminated in turn.

[0578] In FIG. 25, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 210, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0579] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 15A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0580] The antiferromagnetic layer 21, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 25 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first, second or fifth embodiment. Therefore, description of theselayers is omitted.

[0581] As shown in FIG. 25, the free magnetic layer 210 of the spinvalve element 15 comprises a nonmagnetic intermediate layer 216, andfirst and second free magnetic layers 211 and 212 with the nonmagneticintermediate layer 216 provided therebetween. The first and second freemagnetic layers 211 and 212 are antiferromagnetically coupled with eachother with the nonmagnetic intermediate layer 216 provided therebetween.

[0582] The first free magnetic layer 211 is provided in contact with thecapping layer 24 on the side of the nonmagnetic intermediate layer 216,which is opposite to the nonmagnetic conductive layer 29. On the otherhand, the second free magnetic layer 212 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic intermediate layer 216.

[0583] The first free magnetic layer 211 comprises a ferromagneticconductive film which has low resistivity and is ferromagnetic, and madeof, for example, any one of Co, a CoFe alloy, a NiFe alloy, a CoNialloy, and a CoNiFe alloy, preferably a NiFe alloy, preferably a NiFealloy.

[0584] The thickness of the first free magnetic layer 211 is preferablyin the range of 0.5 to 3.5 nm.

[0585] The second free magnetic layer 212 comprises a nonmagneticintermediate insulating film 214, and fourth and fifth ferromagneticconductive films 213 and 215 with the nonmagnetic intermediateinsulating film 214 provided therebetween.

[0586] The fourth ferromagnetic conductive film 213 is provided incontact with the nonmagnetic intermediate layer 216 on the side of thenonmagnetic intermediate insulating film 214, which is opposite to thenonmagnetic conductive layer 29. On the other hand, the fifthferromagnetic conductive film 215 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic intermediate insulating film 214.

[0587] The fourth and fifth ferromagnetic conductive films 213 and 215are brought into the ferrimagnetic state by antiferromagnetic couplingwith the nonmagnetic intermediate insulating film 214 providedtherebetween.

[0588] The fourth and fifth ferromagnetic conductive films 213 and 215comprise a ferromagnetic conductive film which has low resistivity andis ferromagnetic, and made of, for example, any one of Co, a CoFe alloy,a NiFe alloy, a CoNi alloy, and a CoNiFe alloy, preferably a NiFe alloy,preferably a NiFe alloy.

[0589] The nonmagnetic intermediate insulating film 214 is made of anonmagnetic insulating material which has higher resistivity than thefourth and fifth ferromagnetic conductive films 213 and 215.

[0590] The thickness of the fourth ferromagnetic conductive film 213 ispreferably in the range of 1.0 nm to 3.0 nm, the thickness of the fifthferromagnetic conductive film 215 is preferably in the range of 1.5 nmto 4.5 nm, and the thickness of the nonmagnetic intermediate insulatingfilm 214 is preferably in the range of 0.2 nm to 2.0 nm.

[0591] The fourth and fifth ferromagnetic conductive films 213 and 215are preferably formed so that the thickness of any one of both films islarger than that of the other. In FIG. 25, the fourth ferromagneticconductive film 213 is thicker than the fifth ferromagnetic conductivefilm 215.

[0592] The thickness of the entire second free magnetic layer 212 ispreferably in the range of 2.7 nm to 9.5 nm, and larger than that of thefirst free magnetic layer 211.

[0593] The fourth and fifth ferromagnetic conductive films 213 and 215are brought into the ferrimagnetic state by antiferromagnetic coupling.Therefore, when the magnetization direction of the fifth ferromagneticconductive film 215 is oriented in the direction opposite to the X₁direction by the bias layers 332, the magnetization direction of thefourth ferromagnetic conductive film 213 is oriented in the X₁direction. The magnetization of the fourth ferromagnetic conductive film213 remains to orient the magnetization direction of the entire secondfree magnetic layer 212 in the X₁ direction.

[0594] Furthermore, the magnetization direction of the first freemagnetic layer 211 antiferromagnetically coupled with the second freemagnetic layer 212 is oriented in the direction opposite to the X₁direction, and the magnetization of the second free magnetic layer 212remains to orient the magnetization direction of the entire freemagnetic layer 210 in the X₁ direction to form the ferrimagnetic state.

[0595] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 210 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0596] Also, a potential barrier is formed at the interface between thenonmagnetic intermediate insulating film 214 and the fifth ferromagneticconductive film 215 due to a great difference in resistivity betweenboth layers. Of the conduction electrons moving in the nonmagneticconductive layer 29, therefore, up-spin conduction electrons aremirror-reflected by the nonmagnetic intermediate insulating film 214while maintaining the spin direction.

[0597] The up-spin conduction electrons are mirror-reflected at theinterface between the nonmagnetic intermediate insulating film 214 andthe fifth ferromagnetic conductive film 215 to extend the mean freepath. As a result, like in the first embodiment, the difference betweenthe mean free paths of the up-spin conduction electrons and thedown-spin conduction electrons can be increased to increase the rate ofchange in magnetoresistance of the spin valve element 15.

[0598] This is described with reference to a schematic drawing of FIG.26.

[0599]FIG. 26 shows a laminate 15G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, and the second free magnetic layer 212(the fifth ferromagnetic conductive film 215, the nonmagneticintermediate insulating film 214, and the fourth ferromagneticconductive film 213), the nonmagnetic intermediate layer 216, and thefirst free magnetic layer 211 are laminated in turn.

[0600] In FIG. 26, the magnetization direction of the free magneticlayer 210 is oriented in the leftward direction in FIG. 26 by theexternal magnetic field, and the magnetization direction of the pinnedmagnetic layer 30 is pinned in the leftward direction in FIG. 26 by anexchange coupling magnetic field with the antiferromagnetic layer 21.

[0601] When the sensing current is passed through the laminate 15G shownin FIG. 26, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. In FIG. 26, theup-spin conduction electrons are denoted by reference character e₁, andthe down-spin conduction electrons are denoted by reference charactere₂.

[0602] The up-spin conduction electrons e₁ quite possibly move fromnonmagnetic conductive layer 29 to the fifth ferromagnetic conductivefilm 215 when the magnetization directions of the pinned magnetic layer30 and the free magnetic layer 210 are made parallel by the externalmagnetic field.

[0603] The up-spin conduction electrons e₁ move to the interface betweenthe nonmagnetic intermediate insulating film 214 and the fifthferromagnetic conductive film 215, are mirror-reflected by thenonmagnetic intermediate insulating film 214, which forms the potentialbarrier, while maintaining the spin state, and again move in the fifthferromagnetic conductive film 215.

[0604] In this way, the up-spin conduction electrons e₁ pass through thefifth ferromagnetic conductive film 215, the nonmagnetic conductivelayer 29 and the pinned magnetic layer 30 twice each to significantlyextend the mean free path to λ⁺.

[0605] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the fifth ferromagneticconductive film 215, and are maintained in the state where theprobability of movement to the fifth ferromagnetic conductive film 215is low, and the mean free path (λ⁻) remains shorter than the mean freepath (λ⁺) of the up-spin conduction electrons e₁.

[0606] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 15G.

[0607] Therefore, in the spin valve element 15 of this embodiment, themean free path of the up-spin conduction electrons e₁ can besignificantly increased to increase the difference between the mean freepaths of the up-spin conduction electrons e₁ and the mean free path ofthe down-spin conduction electrons e₂, thereby significantly improvingthe rate of change in magnetoresistance of the spin valve element 15.

[0608] Also, the fifth ferromagnetic conductive film 215 is formed incontact with the nonmagnetic conductive layer 29, and thus the greatergiant magnetoresistive effect can be manifested at the interface betweenthe fifth ferromagnetic conductive film 215 and the nonmagneticconductive layer 29.

[0609] The spin valve element 15 is manufactured by substantially thesame method as the spin valve element 5 of the fifth embodiment exceptthat the second free magnetic layer 212 comprises the fourthferromagnetic conductive film 213, the nonmagnetic intermediateinsulating film 214, and the fifth ferromagnetic conductive film 215.

[0610] In the spin valve element 15, the up-spin conduction electronscan be mirror-reflected by the nonmagnetic intermediate insulating film214 to extend the mean free path of the up-spin conduction electrons.Therefore, the difference between the mean free paths of the up-spin anddown-spin conduction electrons can be increased to increase the rate ofchange in magnetoresistance of the spin valve element 15.

[0611] Also, the fifth ferromagnetic conductive film 215 is formed incontact with the nonmagnetic conductive layer 29, and thus the greatergiant magnetoresistive effect can be manifested at the interface betweenthe fifth ferromagnetic conductive film 215 and the nonmagneticconductive layer 29 to further increase the rate of change inmagnetoresistance of the spin valve element 15.

[0612] Furthermore, the first and second free magnetic layers 211 and212 are brought into the ferrimagnetic state, and the fourth and fifthferromagnetic conductive films 213 and 215, which constitute the secondfree magnetic layer 212, are brought into the ferrimagnetic state withthe nonmagnetic intermediate insulating film 214 provided therebetween.Therefore, the entire free magnetic layer 210 can be more stably putinto the ferrimagnetic state.

[0613] Sixteenth Embodiment

[0614] A sixteenth embodiment of the present invention will be describedwith reference to the drawings.

[0615]FIG. 27 is a schematic sectional view of a spin valve element 16according to the sixteenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0616] The spin valve element 16 shown in FIG. 27 is a top-type singlespin valve element in which a free magnetic layer 220, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0617] In FIG. 27, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 220, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0618] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 16A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0619] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (the nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 27 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third, fourth or tenth embodiment. Therefore, description of theselayers is omitted.

[0620] As shown in FIG. 27, the free magnetic layer 220 of the spinvalve element 16 comprises a nonmagnetic intermediate layer 226, andfirst and second free magnetic layers 221 and 222 with the nonmagneticintermediate layer 226 provided therebetween. The first and second freemagnetic layers 221 and 222 are antiferromagnetically coupled with eachother with the nonmagnetic intermediate layer 226 provided therebetween.

[0621] The first free magnetic layer 221 is provided in contact with theunderlying layer 23 on the side of the nonmagnetic intermediate layer226, which is opposite to the nonmagnetic conductive layer 29, while thesecond free magnetic layer 222 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic intermediate layer 226.

[0622] The first free magnetic layer 221 comprises a ferromagneticconductive film which is made of the same material as the first freemagnetic layer of the fifteenth embodiment.

[0623] The thickness of the first free magnetic layer 221 is preferablyin the range of 0.5 to 3.5 nm.

[0624] The second free magnetic layer 222 comprises a nonmagneticintermediate insulating film 224, and fourth and fifth ferromagneticconductive films 223 and 225 with the nonmagnetic intermediateinsulating film 224 provided therebetween.

[0625] The fourth ferromagnetic conductive film 223 is provided incontact with the nonmagnetic intermediate layer 226 on the side of thenonmagnetic intermediate insulating film 224, which is opposite to thenonmagnetic conductive layer 29. On the other hand, the fifthferromagnetic conductive film 225 is provided in contact with thenonmagnetic conductive layer 29 on the nonmagnetic conductive layer 29side of the nonmagnetic intermediate insulating film 224.

[0626] The fourth and fifth ferromagnetic conductive films 223 and 225are brought into the ferrimagnetic state by antiferromagnetic couplingwith the nonmagnetic intermediate insulating film 224 providedtherebetween.

[0627] The fourth and fifth ferromagnetic conductive films 223 and 225comprise a ferromagnetic conductive film of the same material as thefourth and fifth ferromagnetic conductive films of the fifteenthembodiment.

[0628] The nonmagnetic intermediate insulating film 224 is made of anonmagnetic insulating material which has higher resistivity than thefourth and fifth ferromagnetic conductive films 223 and 225.

[0629] The thickness of the fourth ferromagnetic conductive film 223 ispreferably in the range of 1.0 nm to 3.0 nm, the thickness of the fifthferromagnetic conductive film 225 is preferably in the range of 1.5 nmto 4.0 nm, and the thickness of the nonmagnetic intermediate insulatingfilm 224 is preferably in the range of 0.2 nm to 2.0 nm.

[0630] The fourth and fifth ferromagnetic conductive films 223 and 225are preferably formed so that the thickness of any one of both films islarger than that of the other. In FIG. 27, the fourth ferromagneticconductive film 223 is thicker than the fifth ferromagnetic conductivefilm 225.

[0631] The thickness of the entire second free magnetic layer 222 ispreferably in the range of 2.7 nm to 9.5 nm, and larger than that of thefirst free magnetic layer 221.

[0632] The fourth and fifth ferromagnetic conductive films 223 and 225are brought into the ferrimagnetic state by antiferromagnetic coupling.Therefore, when the magnetization direction of the fifth ferromagneticconductive film 225 is oriented in the direction opposite to the X₁direction by the bias layers 332, the magnetization direction of thefourth ferromagnetic conductive film 223 is oriented in the X₁direction. The magnetization of the fourth ferromagnetic conductive film223 remains to orient the magnetization direction of the entire secondfree magnetic layer 222 in the X₁ direction.

[0633] Furthermore, the magnetization direction of the first freemagnetic layer 221 antiferromagnetically coupled with the second freemagnetic layer 222 is oriented in the direction opposite to the X₁direction, and the magnetization of the second free magnetic layer 222remains to orient the magnetization direction of the entire freemagnetic layer 220 in the X₁ direction to form the ferrimagnetic state.

[0634] Even with a small external magnetic field applied, themagnetization direction of the free magnetic layer 220 put into theferrimagnetic state can thus be rotated according to the direction ofthe external magnetic field.

[0635] Also, a potential barrier is formed at the interface between thenonmagnetic intermediate insulating film 224 and the fifth ferromagneticconductive film 225 due to a great difference in resistivity betweenboth layers.

[0636] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, therefore, up-spin conduction electrons are mirror-reflectedby the potential barrier while maintaining the spin direction.

[0637] The up-spin conduction electrons are mirror-reflected by thenonmagnetic intermediate insulating film 224 to extend the mean freepath.

[0638] Namely, the up-spin conduction electrons quite possibly move fromthe pinned magnetic layer 40 to the fifth ferromagnetic conductive film225 through the nonmagnetic conductive layer 29 when the magnetizationdirections of the pinned magnetic layer 40 and the free magnetic layer220 are made parallel by the external magnetic field.

[0639] The up-spin conduction electrons are mirror-reflected at theinterface between the fifth ferromagnetic conductive film 225 and thenonmagnetic intermediate insulating film 224 while maintaining the spinstate, and again move through the fifth ferromagnetic conductive film225, the nonmagnetic conductive layer 29 and the pinned magnetic layer40.

[0640] In this way, the up-spin conduction electrons move through thefifth ferromagnetic conductive film 225, the nonmagnetic conductivelayer 29 and the pinned magnetic layer 40 twice each to significantlyextend the mean free path.

[0641] Like in the first embodiment, in the spin valve element 16 ofthis embodiment, the mean free path of the up-spin conduction electronscan be significantly increased by the mirror-reflecting effect toincrease the difference between the mean free paths of the up-spin anddown-spin conduction electrons. Therefore, the rate of change inmagnetoresistance of the spin valve element 16 can be significantlyimproved.

[0642] In addition, the fifth ferromagnetic conductive film 225 isformed in contact with the nonmagnetic conductive layer 29, and thus thegreater giant magnetoresistive effect can be manifested at the interfacebetween the fifth ferromagnetic conductive film 225 and the nonmagneticconductive layer 29.

[0643] The spin valve element 16 is manufactured by substantially thesame method as the spin valve element 10 of the tenth embodiment exceptthat the second free magnetic layer 222 comprises the fourthferromagnetic conductive film 223, the nonmagnetic intermediateinsulating film 224, and the fifth ferromagnetic conductive film 225.

[0644] The spin valve element 16 exhibits substantially the same effectas the spin valve element 15 of the fifteenth embodiment.

[0645] Seventeenth Embodiment

[0646] A seventeenth embodiment of the present invention will bedescribed with reference to the drawings.

[0647]FIG. 28 is a schematic sectional view of a spin valve element 17according to the seventeenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0648] The spin valve element 17 shown in FIG. 28 is a bottom-typesingle spin valve element in which an antiferromagnetic layer 21, apinned magnetic layer 30, a nonmagnetic conductive layer 29, and a freemagnetic layer 230 are laminated in turn.

[0649] In FIG. 28, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The antiferromagneticlayer 21, the pinned magnetic layer 30, the nonmagnetic conductive layer29, the free magnetic layer 230, and a capping layer 24 are laminated inturn on the underlying layer 23.

[0650] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 17A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0651] The antiferromagnetic layer 21, the nonmagnetic conductive layer29, the pinned magnetic layer 30 (the nonmagnetic layer 33 and first andsecond pinned magnetic layers 31 and 32), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 28 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe first, second or fifth embodiment. Therefore, description of theselayers is omitted.

[0652] The free magnetic layer 230 comprises a nonmagnetic intermediateinsulating layer 233, and first and second free magnetic layers 231 and232 with the nonmagnetic intermediate layer 233 provided therebetween.The first and second free magnetic layers 231 and 232 are brought intothe ferrimagnetic state by antiferromagnetic coupling with each otherwith the nonmagnetic intermediate insulating layer 233 providedtherebetween.

[0653] The first free magnetic layer 231 comprises a ferromagneticconductive film which has low resistivity and is ferromagnetic, and madeof, for example, any one of Co, a CoFe alloy, a NiFe alloy, a CoNialloy, and a CoNiFe alloy, preferably a NiFe alloy, preferably a NiFealloy.

[0654] The thickness of the first free magnetic layer 231 is preferablyin the range of 0.5 to 3.5 nm.

[0655] The second free magnetic layer 232 comprises an anti-diffusionfilm 232A and a ferromagnetic film 232B, which are formed in contactwith the nonmagnetic conductive layer 29 and the nonmagneticintermediate insulating layer 233, respectively.

[0656] The anti-diffusion film 232A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 232B and the nonmagnetic conductive layer 29.

[0657] Like the anti-diffusion film 232A, the ferromagnetic film 232Bcomprises a ferromagnetic conductive film made of, for example, any oneof Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy,preferably a NiFe alloy.

[0658] The thickness of the anti-diffusion film 232A is preferably inthe range of 0.1 to 1.5 nm, and the thickness of the ferromagnetic film232B is preferably in the range of 1.4 to 3.0 nm.

[0659] The thickness of the entire second free magnetic layer 232 ispreferably in the range of 1.5 to 4.5 nm, and more preferably largerthan the first free magnetic layer 231.

[0660] The nonmagnetic intermediate insulating layer 233 is made of anonmagnetic insulating material which has higher resistivity than thefirst and second free magnetic layers 231 and 232.

[0661] The first and second free magnetic layers 231 and 232 are broughtinto the ferrimagnetic state by antiferromagnetic coupling. Therefore,when the magnetization direction of the second free magnetic layer 232is oriented in the X₁ direction by the bias layers 332, themagnetization direction of the first free magnetic layer 231 is orientedin the direction opposite to the X₁ direction. The magnetization of thesecond free magnetic layer 232 remains to orient the magnetizationdirection of the entire free magnetic layer 230 in the X₁ direction.

[0662] Furthermore, a potential barrier is formed at the interfacebetween the second free magnetic layer 232 (the ferromagnetic film 232B)and the nonmagnetic intermediate insulating layer 233 due to a greatdifference in resistivity between both layers. Of the conductionelectrons moving in the nonmagnetic conductive layer 29, therefore,up-spin conduction electrons are mirror-reflected by the nonmagneticintermediate insulating layer 233 while maintaining the spin direction.

[0663] The up-spin conduction electrons are mirror-reflected at theinterface between the ferromagnetic film 232B and the nonmagneticintermediate insulating layer 233 to extend the mean free path. As aresult, like in the first embodiment, the difference between the meanfree paths of the up-spin conduction electrons and the down-spinconduction electrons can be increased to increase the rate of change inmagnetoresistance of the spin valve element 17.

[0664] This is described with reference to a schematic drawing of FIG.29.

[0665]FIG. 29 shows a laminate 17G in which the antiferromagnetic layer21, the pinned magnetic layer 30 (the first pinned magnetic layer 31,the nonmagnetic layer 33, the second pinned magnetic layer 32), thenonmagnetic conductive layer 29, and the second free magnetic layer 232(the anti-diffusion film 232A and the ferromagnetic film 232B), thenonmagnetic intermediate insulating layer 233, and the first freemagnetic layer 231 are laminated in turn.

[0666] In FIG. 29, the magnetization direction of the free magneticlayer 230 is oriented in the leftward direction in FIG. 29 by theexternal magnetic field, and the magnetization direction of the pinnedmagnetic layer 30 is pinned in the leftward direction in FIG. 29 by anexchange coupling magnetic field with the antiferromagnetic layer 21.

[0667] When the sensing current is passed through the laminate 17G shownin FIG. 29, the conduction electrons mainly move in the nonmagneticconductive layer 29 having low electric resistance. In FIG. 29, theup-spin conduction electrons are denoted by reference character e₁, andthe down-spin conduction electrons are denoted by reference charactere₂.

[0668] The up-spin conduction electrons e₁ quite possibly move fromnonmagnetic conductive layer 29 to the second free magnetic layer 232when the magnetization directions of the pinned magnetic layer 30 andthe free magnetic layer 230 are made parallel by the external magneticfield.

[0669] The up-spin conduction electrons e₁ move to the interface betweenthe second free magnetic layer 232 (the ferromagnetic film 232B) and thenonmagnetic intermediate insulating layer 233, are mirror-reflected bythe nonmagnetic intermediate insulating layer 233, which forms thepotential barrier, while maintaining the spin state, and again move inthe second free magnetic layer 232.

[0670] In this way, the up-spin conduction electrons e₁ pass through thesecond free magnetic layer 232, the nonmagnetic conductive layer 29 andthe pinned magnetic layer 30 twice each to significantly extend the meanfree path to λ⁺.

[0671] On the other hand, the down-spin conduction electrons e₂ have thehigh probability that they are always scattered at the interface betweenthe nonmagnetic conductive layer 29 and the second free magnetic layer232 (the ferromagnetic film 232B), and are maintained in the state wherethe probability of movement to the second free magnetic layer 232 islow, and the mean free path (λ⁻) remains shorter than the mean free path(λ⁺) of the up-spin conduction electrons e₁.

[0672] The mean free path (λ⁺) of the up-spin conduction electrons e₁becomes longer than the mean free path (λ⁻) of the down-spin conductionelectrons e₂ due to the action of the external magnetic field,increasing the difference (λ⁺−λ⁻) between the paths to increase the rateof change in magnetoresistance of the laminate 17G.

[0673] Therefore, in the spin valve element 17 of this embodiment, thedifference between the mean free paths of the up-spin conductionelectrons e₁ and the mean free path of the down-spin conductionelectrons e₂ is increased, thereby significantly improving the rate ofchange in magnetoresistance of the spin valve element 17.

[0674] The spin valve element 17 is manufactured by substantially thesame method as the spin valve element 1 of the first embodiment exceptthat the nonmagnetic intermediate insulating layer 233 is formed inplace of the nonmagnetic intermediate layer.

[0675] In the spin valve element 17, the up-spin conduction electronscan be mirror-reflected by the nonmagnetic intermediate insulating layer233 to extend the mean free path of the up-spin conduction electrons.Therefore, the difference between the mean free paths of the up-spin anddown-spin conduction electrons can be increased to increase the rate ofchange in magnetoresistance of the spin valve element 17.

[0676] Furthermore, the first and second free magnetic layers 231 and232, which constitute the free magnetic layer 230, are brought into theferrimagnetic state. Therefore, the magnetization direction of the freemagnetic layer 230 can be changed with the small external magnetic fieldto increase the sensitivity of the spin valve element 17 to the externalmagnetic field.

[0677] Therefore, the spin valve element 17 has the particular effect ofsignificantly increasing the rate of change in magnetoresistance by theeffect of mirror-reflecting up-spin conduction electrons, and increasingthe sensitivity to the external magnetic field by providing the freemagnetic layer 230 in the ferrimagnetic state.

[0678] Eighteenth Embodiment

[0679] An eighteenth embodiment of the present invention will bedescribed with reference to the drawings.

[0680]FIG. 30 is a schematic sectional view of a spin valve element 18according to the eighteenth embodiment of the present invention, asviewed from the magnetic recording medium side.

[0681] The spin valve element 18 shown in FIG. 30 is a top-type singlespin valve element in which a free magnetic layer 240, a nonmagneticconductive layer 29, a pinned magnetic layer 40, and anantiferromagnetic layer 22 are laminated in turn.

[0682] In FIG. 30, reference numeral 164 denotes a lower gap layer, andreference numeral 23 denotes an underlying layer. The free magneticlayer 240, the nonmagnetic conductive layer 29, the pinned magneticlayer 40, the antiferromagnetic layer 22, and a capping layer 24 arelaminated in turn on the underlying layer 23.

[0683] In this way, the layers from the underlying layer 23 to thecapping layer 24 are laminated in turn to form a laminate 18A having asubstantially trapezoidal sectional shape having a width correspondingto the track width.

[0684] The antiferromagnetic layer 22, the nonmagnetic conductive layer29, the pinned magnetic layer 40 (a nonmagnetic layer 43 and first andsecond pinned magnetic layers 41 and 42), the bias underlying layers331, the bias layers 332, the intermediate layers 333, and the electrodelayers 334 shown in FIG. 30 have the same constructions and are made ofthe same materials as the antiferromagnetic layer, the nonmagneticconductive layer, the pinned magnetic layer (the nonmagnetic layer andfirst and second pinned magnetic layers), the bias underlying layers,the bias layers, the intermediate layers, and the electrode layers ofthe third, fourth or tenth embodiment. Therefore, description of theselayers is omitted.

[0685] The free magnetic layer 240 comprises a nonmagnetic intermediateinsulating layer 243, and first and second free magnetic layers 241 and242 with the nonmagnetic intermediate insulating layer 243 providedtherebetween. The first and second free magnetic layers 241 and 242 arebrought into the ferrimagnetic state by antiferromagnetic coupling withthe nonmagnetic intermediate insulating layer 243 provided therebetween.

[0686] The first free magnetic layer 241 comprises a ferromagneticconductive film which has low resistivity and is ferromagnetic, andwhich is made of the same material as the first free magnetic layer ofthe seventeenth embodiment.

[0687] The thickness of the first free magnetic layer 241 is preferablyin the range of 0.5 to 3.5 nm.

[0688] The second free magnetic layer 242 comprises an anti-diffusionfilm 242A and a ferromagnetic film 242B, which are formed in contactwith the nonmagnetic conductive layer 29 and the nonmagneticintermediate insulating layer 243, respectively.

[0689] The anti-diffusion film 242A comprises a ferromagnetic conductivefilm of Co or the like, and prevents mutual diffusion between theferromagnetic film 242B and the nonmagnetic conductive layer 29.

[0690] Like the anti-diffusion film 242A, the ferromagnetic film 242Bcomprises a ferromagnetic conductive film made of, for example, any oneof Co, a CoFe alloy, a NiFe alloy, a CoNi alloy, and a CoNiFe alloy,preferably a NiFe alloy.

[0691] The thickness of the anti-diffusion film 242A is preferably inthe range of 0.1 to 1.5 nm, and the thickness of the ferromagnetic film242B is preferably in the range of 1.4 to 3.0 nm.

[0692] The thickness of the entire second free magnetic layer 242 ispreferably in the range of 1.5 to 4.5 nm, and more preferably largerthan the first free magnetic layer 241.

[0693] The nonmagnetic intermediate insulating layer 243 is made of anonmagnetic insulating material which has higher resistivity than thefirst and second free magnetic layers 241 and 242.

[0694] The first and second free magnetic layers 241 and 242 are broughtinto the ferrimagnetic state by antiferromagnetic coupling. Therefore,when the magnetization direction of the second free magnetic layer 242is oriented in the X₁ direction by the bias layers 332, themagnetization direction of the first free magnetic layer 241 is orientedin the direction opposite to the X₁ direction. The magnetization of thesecond free magnetic layer 242 remains to orient the magnetizationdirection of the entire free magnetic layer 240 in the X₁ direction.

[0695] Furthermore, a potential barrier is formed at the interfacebetween the second free magnetic layer 242 (the ferromagnetic film 242B)and the nonmagnetic intermediate insulating layer 243 due to a greatdifference in resistivity between both layers.

[0696] Of the conduction electrons moving in the nonmagnetic conductivelayer 29, therefore, up-spin conduction electrons are mirror-reflectedby the potential barrier while maintaining the spin direction.

[0697] The up-spin conduction electrons are mirror-reflected by thenonmagnetic intermediate insulating layer 243 to extend the mean freepath.

[0698] Namely, the up-spin conduction electrons quite possibly move fromthe pinned magnetic layer 40 to the second free magnetic layer 242through the nonmagnetic conductive layer 29 when the magnetizationdirections of the pinned magnetic layer 40 and the free magnetic layer240 are made parallel by the external magnetic field.

[0699] The up-spin conduction electrons are mirror-reflected at theinterface between the second free magnetic layer 242 (the ferromagneticfilm 242B) and the nonmagnetic intermediate insulating layer 243 whilemaintaining the spin state, and again move through the second freemagnetic layer 242, the nonmagnetic conductive layer 29 and the pinnedmagnetic layer 40.

[0700] In this way, the up-spin conduction electrons move through thesecond free magnetic layer 242, the nonmagnetic conductive layer 29 andthe pinned magnetic layer 40 twice each to significantly extend the meanfree path.

[0701] Like in the first embodiment, therefore, in the spin valveelement 18 of this embodiment, the mean free path of the up-spinconduction electrons can be significantly increased by themirror-reflecting effect to increase the difference between the meanfree paths of the up-spin and down-spin conduction electrons. Therefore,the rate of change in magnetoresistance of the spin valve element 18 canbe significantly improved.

[0702] The spin valve element 18 is manufactured by substantially thesame method as the spin valve element 3 of the third embodiment exceptthat the nonmagnetic intermediate insulating film 243 is formed in placeof the nonmagnetic intermediate layer.

[0703] The spin valve element 18 exhibits substantially the same effectas the spin valve element 17 of the seventeenth embodiment.

[0704] As described in detail above, in the spin valve element of thepresent invention of the present invention, a free magnetic layercomprises a nonmagnetic intermediate layer, and first and second freemagnetic layers with the nonmagnetic intermediate layer providedtherebetween, the second free magnetic layer being formed in contactwith the nonmagnetic conductive layer. Also the first and second freemagnetic layers are put into the ferrimagnetic state byantiferromagnetic coupling with each other, and one of the first andsecond free magnetic layers comprises a ferromagnetic insulating film.In the case where the first free magnetic layer comprises theferromagnetic insulating film, the first free magnetic layer has higherresistivity, and the sensing current less flows through the first freemagnetic layer to suppress a shunt of the sensing current. Therefore,the shunt loss can be decreased to increase the rate of change inmagnetoresistance of the spin valve element.

[0705] Since the ferromagnetic insulating film has high resistivity,contact with another layer of low resistivity forms a potential barrierat the interface between both layers. As a result, up-spin conductionelectrons are mirror-reflected to extend the mean free path of theup-spin conduction electrons, thereby further increasing the rate ofchange in magnetoresistance of the spin valve element.

[0706] In the spin valve element of the present invention, with thesecond free magnetic layer comprising a ferromagnetic insulating film,the up-spin conduction electrons are mirror-reflected by theferromagnetic insulating film to extend the mean free path of theup-spin conduction electrons. Also the up-spin conduction electrons aretrapped near the nonmagnetic conductive layer to suppress a shunt of thesensing current, decreasing the shunt loss. Therefore, the rate ofchange in magnetoresistance of the spin valve element can be furtherincreased.

[0707] In the spin valve element of the present invention, the freemagnetic layer comprises the nonmagnetic intermediate layer, and thefirst and second free magnetic layers with the nonmagnetic intermediatelayer provided therebetween, and the first and second free magneticlayers are put into the ferrimagnetic state by antiferromagneticcoupling with each other. The second free magnetic layer may comprise apair of ferromagnetic films which are brought into the ferrimagneticstate by antiferromagnetic coupling with each other. Therefore, theentire free magnetic layer is more stably put into the ferrimagneticstate, and the up-spin conduction electrons are mirror-reflected by theinterface between a nonmagnetic intermediate insulating film having highresistivity and one of the ferromagnetic films to extend the mean freepath of the up-spin conduction electrons. Therefore, the sensitivity toan external magnetic field can be increased, and the rate of change inmagnetoresistance can be improved.

[0708] In the spin valve element of the present invention, the freemagnetic layer may comprise a nonmagnetic intermediate insulating layer,and first and second free magnetic layers with the nonmagneticintermediate insulating layer provided therebetween, and the first andsecond free magnetic layers are put into the ferrimagnetic state byantiferromagnetic coupling with each other. Therefore, the up-spinconduction electrons are mirror-reflected by the interface between thenonmagnetic intermediate insulating film having high resistivity and thesecond free magnetic layer to extend the mean free path of the up-spinconduction electrons. Therefore, the sensitivity to an external magneticfield can be increased, and the rate of change in magnetoresistance canbe improved.

What is claimed is:
 1. A spin valve element comprising anantiferromagnetic layer, a pinned magnetic layer formed in contact withthe antiferromagnetic layer so that the magnetization direction thereofis pinned by an exchange coupling magnetic field with theantiferromagnetic layer, a nonmagnetic conductive layer in contact withthe pinned magnetic layer, and a free magnetic layer in contact with thenonmagnetic conductive layer; wherein the free magnetic layer comprisesa nonmagnetic intermediate layer, and first and second free magneticlayers with the nonmagnetic intermediate layer provided therebetween,the second free magnetic layer is formed in contact with the nonmagneticconductive layer, the first and second free magnetic layers areantiferromagnetically coupled with each other to bring both layers intoa ferrimagnetic state, and either of the first and second free magneticlayers comprises a ferromagnetic insulating film.
 2. A spin valveelement according to claim 1 , wherein the first free magnetic layercomprises only the ferromagnetic insulating film.
 3. A spin valveelement according to claim 1 , wherein the first free magnetic layerpreferably comprises a laminate of the ferromagnetic insulating film anda first ferromagnetic conductive film, the first ferromagneticconductive film is formed in contact with the nonmagnetic intermediatelayer, and the ferromagnetic insulating film and the first ferromagneticconductive film are ferromagnetically coupled with each other to bringboth films into a ferromagnetic state.
 4. A spin valve element accordingto claim 1 , wherein the first free magnetic layer comprises only thefirst ferromagnetic conductive film.
 5. A spin valve element accordingto claim 3 , wherein the thickness s of the first ferromagneticconductive film is in the range of 0 nm<s≦3.0 nm.
 6. A spin valveelement according to claim 1 , wherein the second free magnetic layercomprises only the ferromagnetic insulating film.
 7. A spin valveelement according to claim 1 , wherein the second free magnetic layercomprises a laminate of the ferromagnetic insulating film and a secondferromagnetic conductive film, the second ferromagnetic conductive filmis formed in contact with the nonmagnetic intermediate layer, and theferromagnetic insulating film and the second ferromagnetic conductivefilm are ferromagnetically coupled with each other to bring both filmsinto a ferromagnetic state therebetween.
 8. A spin valve elementaccording to claim 1 or 4 , wherein the second free magnetic layercomprises a laminate of the ferromagnetic insulating film and a thirdferromagnetic conductive film, the third ferromagnetic conductive filmis formed in contact with the nonmagnetic conductive layer, and theferromagnetic insulating film and the third ferromagnetic conductivefilm are ferromagnetically coupled with each other to bring both filmsinto the ferromagnetic state.
 9. A spin valve element according to claim1 or 4 , wherein the second free magnetic layer comprises theferromagnetic insulating film, and the second and third ferromagneticconductive films with the ferromagnetic insulating film providedtherebetween, which are ferromagnetically coupled with each other tobring the films into the ferromagnetic state.
 10. A spin valve elementaccording to claim 1 , wherein the second free magnetic layer comprisesonly the second ferromagnetic conductive film.
 11. A spin valve elementaccording to claim 1 , wherein the ferromagnetic insulating film is aferromagnetic insulating oxide film or ferromagnetic insulating nitridefilm.
 12. A spin valve element according to claim 11 , wherein theferromagnetic insulating film is a ferromagnetic insulating oxide filmcomposed of Fe—O or M—Fe—O (wherein M is at least one element of Mn, Co,Ni, Ba, Sr, Y, Gd, Cu, and Zn).
 13. A spin valve element according toclaim 11 , wherein the ferromagnetic insulating film is a ferromagneticinsulating oxide film comprising a mixture of a fine crystal phase ofbcc structure Fe having an average crystal grain diameter of 10 nm orless and an amorphous phase containing large amounts of element M or M′and O (wherein M represents at least one element of the rare earthelements, and M′ represents at least one element of Ti, Zr, Hf, V, Nb,Ta, and W), and the ratio of the fine crystal phase of bcc structure Feto the entire structure is 50% or less.
 14. A spin valve elementaccording to claim 11 , wherein the ferromagnetic insulating film is aferromagnetic insulating nitride film comprising a fine crystal phasemainly composed of bcc structure Fe having an average crystal graindiameter of 10 nm or less and an amorphous phase mainly composed of acompound of N and at least one element M selected from the groupconsisting of the rare earth metal elements, Ti, Zr, Hf, V, Nb, Ta, andW, and the ratio of the amorphous phase is 50% or more of the structure.15. A spin valve element according to claim 6 , wherein the thickness uof the ferromagnetic insulating film is in the range of 0.5 nm≦u≦10 nm.16. A spin valve element comprising an antiferromagnetic layer, a pinnedmagnetic layer formed in contact with the antiferromagnetic layer sothat the magnetization direction thereof is pinned by an exchangecoupling magnetic field with the antiferromagnetic layer, a nonmagneticconductive layer in contact with the pinned magnetic layer, and a freemagnetic layer in contact with the nonmagnetic conductive layer; whereinthe free magnetic layer comprises a nonmagnetic intermediate layer, andfirst and second free magnetic layers with the nonmagnetic intermediatelayer provided therebetween, the second free magnetic layer is formed incontact with the nonmagnetic conductive layer, the first and second freemagnetic layers are antiferromagnetically coupled with each other tobring both layers into a ferrimagnetic state, and the second freemagnetic layer comprises a nonmagnetic intermediate insulating film anda pair of ferromagnetic conductive films which are antiferromagneticallycoupled with each other to bring both films into a ferrimagnetic state.17. A spin valve element comprises an antiferromagnetic layer, a pinnedmagnetic layer formed in contact with the antiferromagnetic layer sothat the magnetization direction thereof is pinned by an exchangecoupling magnetic field with the antiferromagnetic layer, a nonmagneticconductive layer in contact with the pinned magnetic layer, and a freemagnetic layer in contact with the nonmagnetic conductive layer; whereinthe free magnetic layer comprises a nonmagnetic intermediate insulatinglayer, and first and second free magnetic layers with the nonmagneticintermediate insulating layer provided therebetween, and the first andsecond free magnetic layers are antiferromagnetically coupled with eachother to bring both layers into a ferrimagnetic state.